Linux, Apache, MySQL and PHP, or LAMP as they’re more affectionately known, are a collection of software packages that form the infrastructure supporting much of the World Wide Web. They have become the most common software packages used for web servers around the world today and moreover, they’re FREE!

While the individual software components that comprise a LAMP system are intrinsically separate, together their synergy offers a web server solution that is certainly much more than the sum of its individual parts. In fact, LAMP is so popular that it has almost become the de facto standard for web server systems across the globe.

Built upon open source and essentially free software, it is easy to see why LAMP has become so rapidly accepted by web hosting organisations as their server software system of choice. Furthermore, being free, there’s no reason not to try it for yourself and if you don’t get on with it, then you haven’t wasted any of your hard earned pennies in the process.

Letting the Genie Out

The term LAMP was first coined in 1998 (just seven years after Linux burst on to the scene) by Michael Kunze, who proposed that a bundle of free software packages could effectively rival commercially available software as a serious alternative for the implementation of a commercial-grade web server.

Since then, LAMP has gone from strength to strength, with many versions of Linux now bundling the ubiquitous Apache, MySQL and PHP packages with their operating system as standard.

Linux

Most software packages run on top of an underlying core suite of software programs that provide basic system functions at the heart of the computer. This suite of core programs is more commonly referred to as the operating system.

While Microsoft operating systems, such as Windows XP and Vista, are well known to most people in the home environment, other operating systems are in abundance commercially, such as the “Unix like” Linux operating system.

Linux is a free, open source operating system upon which much of the world’s web servers are based and which is the core of the LAMP suite of packages.

Apache

Apache is a free web server that runs on Linux, amongst many other operating systems.

To say that Apache is the most popular web server and forms much of the infrastructure of the World Wide Web is not an idle statement.

Since 1996, Apache has consistently been the most popular web server on the internet and as of the time of writing, Apache serves over 60% of the world’s websites and in 2009 became the first web server to serve over 100 million web sites.

Unfortunately, web servers aren’t particularly inspiring things, they just do what they say on the tin: serve web pages. Rather, it’s the additional software packages integrated with the web server that really do the “interesting” and “useful” stuff such as the scripting (programming) languages like PHP and the database systems like MySQL.

MySQL

MySQL is an enterprise class (big and professional) relational database management system (RDBMS). This again is free software that provides multi-user access to multiple databases, which in turn can support a host of websites simultaneously.

MySQL uses the industry standard Structured Query Language (SQL) to perform queries and return results from its databases.

Just because it’s free though, doesn’t mean it’s sub standard. MySQL is scalable and is the database system of choice for many large, well known web services such as YouTube, Facebook, Flickr and Wikipedia.

So, if you’re developing a website using a LAMP server with a MySQL database and are worried about how well the system would cope with high traffic, don’t be. It will be more than capable of meeting your potential needs.

PHP

While the ‘P’ of the LAMP acronym can refer to web scripting languages such as Perl and Python, it most commonly refers to the PHP language.

PHP was created in 1995, since which its popularity has grown steadily. It is now being used on over 20 million websites, running on over 1 million web servers!

Like MySQL, PHP is free software and is also capable of supporting professional high volume sites, some examples of which include YouTube, Facebook and Wikipedia.

PHP programs run on a web server and PHP is therefore known as a server side scripting language, compared to JavaScript for example, which normally runs in a user’s web browser.

PHP programs running on a web server act a bit like the glue between the database and the web pages. When a user requests a web page, the PHP script talks to the database to gather the data it requires based on the user’s request. Once it has this data, the script then puts together a web page with the required data and sends it to the user’s web browser.

In this way PHP is said to generate dynamic web pages based on user’s input, compared to standard fixed, or static HTML web pages that can’t be adjusted on the fly in such a manner.

In Summary

Running a LAMP server is a cheap, reliable and moreover scalable way of hosting multiple, dynamic websites.

A LAMP server can be used to run a single, simple website at home if you wish on an old spare PC with no software costs.

Alternatively, the same software could be run on a multi-processor, ninja server and be used to host a plethora of different websites or one large, multi-user, globally accessible web site.

Clearly the choice is up to you, but if you start off small and your project takes off, then LAMP can be with you all the way.

Happy website building…

Manufacturers like to develop and retain technologies that gives them a commercial and technological advantage over their competitors. To this end we as consumers have ended up with a collection of competing, but unfortunately technically incompatible, solutions to the same problem; that of storing large amounts of audio on portable audio players.

Thankfully the majority of manufacturers (but by no means all) of these portable audio players have eased our potential incompatibility problems by making sure that their players can play the majority of compressed audio formats that are in common usage today.

So what are these common compressed audio formats, why do we need them and what are the associated problems with having so many different formats?

Why Compress?

Back in the dark ages of computing, not so long ago, computer memory was not so plentiful, or cheap as it is today. As such, storing large amounts of data, such as audio files, was very costly.

As necessity is the mother of invention, the limited quantities of computer memory available prompted the white coated technical boffins to develop fiendishly cunning ways of throwing away most of the audio data from these files, while still retaining a high level of perceived audio quality.

How they do this is rather complicated, but they essentially save space by not storing the bits of the music that we can’t hear. During compression of a 128 kbits/s MP3 file, typically 90% of the audio data is discarded, leaving a file size of one tenth of the original size. This in turn means that your MP3 player is able to store ten times the amount of songs compared to if it had to store the original uncompressed CD data.

MP3

MP3 (MPEG-1 Audio Layer 3) is by far the most well known out of all of the audio compression systems available today, and while it may not be as technologically advanced as some of the newer systems, it is the most widely used and provides perfectly adequate results for moderate bit rates for the majority of people’s requirements.

The major benefit of encoding your audio files in MP3 format is that you are pretty much guaranteed you’ll be able to play your resultant files on almost any modern media player or device. It is for this reason that most podcasts choose to adopt the MP3 format as their preferred compression system.

While most people think that MP3 is a free and open source format, it’s not! There are numerous patents owned by a host of different organisations that are applicable to the MP3 technology. This can make official licensing of MP3 technology for use in encoding software or playback devices quite tortuous. Out of all of the organisations that lay claim to the technology underlying MP3s, the German Fraunhofer Society is probably the most notable.

AAC

AAC (Advanced Audio Coding) is actually part of the MPEG-2 and MPEG-4 specifications and is designed to be a superior technological replacement for the older MP3 format. AAC is designed to provide improved sonic quality and transparency compared to MP3 files encoded at the same bit rate, although this advantage only becomes dominant for lower bit rates (below 128 kbits/s).

AAC is the default format that Apple have adopted for their iPods, iPhone and iTunes and for their iTunes online music store.  Sony has also adopted AAC as the standard audio encoding system for their PlayStation 3 and has been incorporated into their PlayStation Portable and recent Sony Walkman systems. Other companies adopting this format include Nokia and Nintendo (Wii and DSi).

WMA

WMA (Windows Media Audio) is Microsoft’s proprietary audio compression system built into its Windows operating system and is the default compression option used for ripping CDs to your computer using Windows Media Player.

Whilst WMA is a proprietary Microsoft system, the technology has been licensed by numerous third parties meaning that if you’ve ripped your entire CD collection onto your computer’s hard drive in WMA format (as I have), then you have a good chance of being able to play these WMA encoded audio files on a host of compatible devices.

I have a Creative Zen MP3 player, which plays WMA files without any problems and I also have two Netgear MP101 media players at home linked to my home network that can stream music from my server in WMA format.

ATRAC

ATRAC (Adaptive Transform Acoustic Coding) is another proprietary audio compression format, this time developed by Sony, originally for their MiniDisc systems in the early 1990s, but has since been used in the company’s range of portable audio players.

Since its inception, ATRAC’s compression algorithm has been improved over the intervening years, with the newer versions offering improved perceived audio quality over earlier versions for similar bit rates.

Unfortunately, ATRAC encoded files are not widely supported by other manufacturers and as such, if you have a Sony branded audio player and have ripped all of your CD selection into ATRAC files, you’ll be extremely limited as to where else you can play your audio files.

Licence Free

Ogg Vorbis

While the Ogg Vorbis audio compression format is not hugely popular outside of the geeky computer nerd circles, it is worth a brief mention as a number of commercial “MP3  players” support the format. More importantly though is the Ogg Vorbis system is FREE!

There are no patents or licence issues to worry about if you choose to adopt this system, although compatibility with other media playback devices may prove to be an issue.

FLAC

FLAC (Free Lossless Audio Codec) is another audio compression system worth a mention, partly because it’s free (as its name suggests) and partly because it’s lossless.

All of the above compression systems loose some audio quality in their compression process. FLAC does not, but the downside is that the same sort of compression levels are not achievable.

FLAC files tend to be between 40 to 50% the size of the original audio file, which is not that impressive compared to a typical 10% figure of an MP3 file.

Like anything in life, it’s a balancing act. If you can afford the additional storage space required and want original quality audio, then FLAC is the way to go. For the majority of people however, these tiny improvements in audio quality compared to the space saving benefits of any of the above compression formats will not be worth the penalty of compatibility issues.

Summary

While MP3 is the most common and well known of all the audio compression systems, it’s by no means the best. There are a multitude of different audio compression systems available, with just a handful of the most common ones mentioned above.

The choice of compression system can depend on many factors, but for most people, providing the audio quality is reasonably good and the file sizes acceptably small the overriding issue will probably be compatibility.

By now you’ve probably heard of the term “bit rate” used in connection with MP3 tracks and podcasts, you may even know that higher bit rates give better quality audio. However, like most things in life, nothing is simple and we can further complicate the whole bit rate discussion with variable and constant bit rates. So, what are the pros and cons of these constant and variable bit rates?

Choosing a bit rate for a podcast, or an MP3 track, is a bit of a balancing act at the best of times. On the one hand, higher bit rates (variable or constant) give improved audio quality, whilst on the other they lead to bigger file sizes.

Introducing yet another variable into the equation, that of constant or variable bit rates, only serves to confuse the situation even further. What then are the relative pros and cons that may affect your choice of type of bit rate to use?

Balancing Bit Rates

If you’re not familiar with bit rates, then my previous post on What are bit rates? should point you in the right general direction and help to get you started.

In essence, higher bit rates give improved audio quality, no matter whether variable or constant bit rates are used. However, higher bit rates will always lead to larger file sizes, which in turn lead directly to longer download times and require more storage space.

When choosing which bit rate to use for your podcast or MP3 track, you really need to go for the highest bit rate possible, while retaining reasonable file sizes and practical download times.

Accepting the fact that you need to choose the highest practical bit rate you can, which option should you go for next (assuming your encoding software gives you the option) constant or variable bit rates?

Constant Bit Rates

Constant Bit Rates (CBR) are pretty much as their name suggests, where one fixed, or constant bit rate is used for the entire file or track.

However, constant bit rates are not optimal as they waste valuable data bits encoding simple sections of audio, and conversely may not use sufficient data bits on more complex audio passages, resulting in poorer audio quality during these sections.

The more complex audio sections of tracks encoded with a constant bit rate will be of a lower audio quality compared to the more simple sections of audio within the same track, so a suitable bit rate must be chosen that provides sufficient audio quality for the most demanding sections of the audio being encoded.

Constant bit rates are easier and therefore faster to encode compared to variable bit rates and lead to consistent and predictable file sizes. Being an older format, constant bit rates are more compatible with older MP3 players.

Variable Bit Rates

Variable Bit Rates (VBR) are likewise pretty much as their name suggests, where the bit rate may change throughout the file or track being encoded.

Variable bit rate encoding analyses the audio file, adapting the bit rate as it goes to match the complexity of the audio it encounters.

For simple audio passages, the system automatically turn its bit rate down, saving valuable data bits, while retaining the perceived audio quality. Conversely, during more complex passages, the system automatically turns its bit rate up, using more data bits to retain the same level of audio quality.

Using this method, the average audio quality of a file can be increased as the available data bits are used more flexibly to encode the sound data with increased overall accuracy.

When encoding an MP3 track or podcast with the VBR method, the encoding software usually allows you to decide on the overall quality of the resulting track that you desire, after which the system encoder uses the bits required to achieve this defined quality level. Higher quality levels will require more bits.

Compared to constant bit rates, variable bit rates produce smaller file sizes for a given audio quality. However, as the bit rates are variable, it’s difficult to predict the size off these files in advance.

Variable bit rates are harder and therefore slower to encode compared to constant bit rates, as the adaptive encoding process is more complex an processor intensive.

Being a more recent encoding method, some older MP3 players or computer software may not be compatible with variable bit rate encoded MP3 tracks or podcasts.

Constrained Variable Bit Rates

A Constrained Variable Bit Rate (CVBR) is a flavour of variable bit rate, where the maximum bit rate allowed, or the Average Bit Rate (ABR) are predefined.

For example, encoding an audio track with the bit rate set to be an average of 128kbps should produce a resultant audio file of higher perceived quality than the same track of encoded at 128kbps CBR, as the ABR file can use data bits it saved during the simpler passages to add extra data bits (above the 128kbps average) to the more complex passages to improve the overall audio quality.

Which to Use and When

Compatibility

Generally speaking, encoding an MP3 track or podcast using a constant bit rate will be better for the sake of compatibility compared to using a variable bit rate, as some older MP3 players don’t support variable bit rates.

By way of example, in their guidelines for broadcast media, the BBC recommends the use of constant bit rates for their all of their podcasts and downloadable audio files.

Quality

If compatibility isn’t a significant issue for you, then you will probably be better off using a form of variable bit rate of encoding to squeeze the best audio quality that you can out of the available bits.

Whether you choose to use a constrained variable bit rate, so that you can keep a handle on the size of file you’re likely to get, or go for a fully variable bit rate, is entirely up to you.

However, before fixing which method you’re going to use, it may be best to do a few test recordings using different bit rates and bit rate types, before deciding on which suits your purposes best.

In Summary

The internet has a language all of its own and online marketing is certainly no exception. So, if you’re thinking of advertising your business online and fall at the first hurdle with all of the jargon you encounter, then this article should help get you on your way.

If you decide to advertise your business on-line, you will undoubtedly come across a whole new language associated with this form of marketing. The most commonly used of these jargon words and phrases however, tend to relate to the different charging mechanisms that are available for on-line advertising campaigns.

While there are a host of terms and phrases used in the online marketing industry, only the most common are covered here, such as PPC, CPM, CTR etc.. However, while this post offers a brief introduction to these terms, it does not provide any in-depth explanation as to the best systems to use or how to use them, as this will often vary depending on your specific circumstances and requirements.

PPC – Pay Per Click

Pay Per Click (PPC) is by far the most common method of paying for advertising on the internet, partly due to the popularity of the Google AdWords system. While you may not have heard of Google AdWords directly, you will probably have seen their adverts on numerous websites (including this one), with the text “Ads by Google” next to them. For example, the advert below was displayed on my Plant Advice website by Google AdWords:

Using Google AdWords as a PPC service to advertise your company, your adverts will be displayed on websites appropriate to your company and products. For example, if your company sells plants on-line and you are specifically promoting grasses, the ad system will try to place your adverts on pages that relate to grasses.

Using this method, you only pay when somebody actually clicks on your advert. Your advert may be displayed thousands of times, yet if nobody clicks on your advert, it won’t cost you a penny! This can be quite a cost effective method of advertising, as you’re only paying for traffic that is actually brought to your website.

CPC – Cost Per Click

Using a PPC service to advertise your company or product, you will be charged for every click on your advert. The CPC, or Cost Per Click, is the cost that you will be charged for each of these clicks.

The cost of each click can vary tremendously depending on which advertising service you use and how competitive the advertising is in the market area that you are targeting. Typical values are in the order of $0.10 to $1.00.

For example, if you spent $100 on a PPC advertising campaign and your advert was clicked on 80 times, your effective cost per click would be:

CPC = Total Campaign Cost ÷ Number of Clicks

CPC = $100 ÷ 80 = $1.25

CPI – Cost Per Impression

An alternative online advertising method to the PPC system, is one where you get charged every time your advert is displayed, whether it gets clicked on or not. The cost per impression is the cost to you for every advertisement shown on a website.

For example, if you agreed to have your advert displayed on a website 10,000 times and you were charged $100 for this, the effective cost per impression would be:

CPI = Total Campaign Cost ÷ Number of Impressions

CPI = $100 ÷ 10,000 = $0.01

That is, it would cost you $0.01 every time your advert was displayed.

CPM – Cost Per Thousand Impressions

Popular websites can display thousands of pages each day, as such, rather than using the CPI figure above, a version more appropriate to the large number of pages typically viewed on a website is CPI’s big brother; CPM.

CPM is the cost that you will pay for every 1,000 advertisements shown on a website. The M comes from the Latin for 1,000; mille, also from the Roman numeral for 1,000, which is M.

For example, if you pay $100 for a website advertisement, which 10,000 people see, the effective cost for 1,000 impressions would be:

CPM = (Total Campaign Cost ÷ Number of Impressions) x 1,000

CPM = ($100 ÷ 10,000) x 1,000 = $10.00

or

CPM = CPI x 1,000 = $0.01 x 1,000 = $10.00

That is, it would cost you $10.00 for every 1,000 adverts displayed.

CPM tends to be used in preference to CPI in the online marketing world.

CTR – Click Through Ratio

The Click Through Ratio, or Click Through Rate is the percentage of users who click on a viewed advertisement and is usually a good indication of the effectiveness of an advertisement. The more people that click on an advert, the more successful the ad.

Average click-through-rates vary depending upon the type of site and visitors, but are typically of the order of 1%, or 1 in every 100 visitors clicking on the advert.

A click through ratio can be calculated by dividing the number of times the advert was clicked on by the number of impressions (number of times the advert was displayed) then multiplying by 100 to get the percentage.

For example, if an advert was displayed 10,000 times and 80 people clicked on the ad, the effective click through rate would be:

CTR = (Number of Clicks ÷ Number of Impressions) x 100

CTR = (80 ÷ 10,000) x 100 = 0.8%

Mixing It Up

As an example to see how all of these terms can be inter-related, let’s assume that we took out an advert with a website to display our ad 10,000 times, which cost us $100. After running this campaign, we measured that the advert was clicked on 80 times. From this we can calculate the following:

CPI = $100 ÷ 10,000 impressions = $0.01

CPM = CPI x 1,000 = $0.01 x 1,000 = $10.00

or CPM = ($100 ÷ 10,000 impressions) x 1,000 = $10.00

CTR = (80 clicks ÷ 10,000 impressions) x 100 = 0.8%

CPC = $100 ÷ 80 clicks = $1.25

Quick Refresher

Hopefully this handful of three lettered, online marketing acronyms now makes a little more sense and don’t seem quite so daunting. So, in future, when you see any of the following, you should have a good idea of what’s going on:

• PPC – Pay Per Click
• CPC – Cost Per Click
• CPI – Cost Per Impression
• CPM – Cost Per Thousand Impressions
• CTR – Click Through Ratio

And to calculate any of these values, you can use the following formulae:

• CPC = Total Campaign Cost ÷ Number of Clicks
• CPI = Total Campaign Cost ÷ Number of Impressions
• CPM = (Total Campaign Cost ÷ Number of Impressions) x 1,000
• CPM = CPI x 1,000
• CTR = (Number of Clicks ÷ Number of Impressions) x 100

Social media, new media, web 2.0; whatever you choose to call it, there are now so many ways of keeping in contact with friends and family and keeping up to date with the latest news and events, that you could spend all day doing just this and not achieving anything productive.

So how do you choose which of the latest new media offerings to adopt, and which are the ones that are likely to stand the test of time and become mainstream?

Who’s Auntie?

In referring to Auntie, I’m actually referring to the BBC, but why Auntie?

Well, for some strange historical reason, here in the UK the BBC is affectionately known as Auntie, or Auntie Beeb.

Why Follow the BBC?

Radio

The BBC have been in broadcasting for an awfully long time, since 1922 in fact, and they are the world’s largest and most respected broadcaster. The BBC have always been keen to adopt new and emerging technologies as transmission media for their news and entertainment offerings.

Television

In 1932 the BBC commenced transmissions on the then new fangled television, at the time having no real concept of what a global and ubiquitous format this would prove to be. In 1967 the they started transmitting television signals in colour and in 1974 added the teletext service to their TV signals.

Internet

Being an early adopter of emerging technologies, the BBC first embraced the internet with an online presence for some of its shows in 1994. Bearing in mind that this was only two years after the public release of the world wide web, this definitely shows their foresight in adopting this new medium.

In December 1997, the BBC officially launched BBC Online, which has gone from strength to strength since, with the website now containing over two million pages and being one of the most visited and popular websites in the world.

Web 2.0

While the term web 2.0 is quite common, its actually very difficult to pin down exactly what it means. In common parlance, it generally refers to the modern, interactive nature of the web, for example social networking sites, blogs, podcasts and RSS feeds.

Since their first foray into the wonderful world wide web, the BBC have been early adopters in many new internet technologies such as RSS, blogs, podcasts and even social media websites.

The BBC obviously do their research before moving into any new area. As such, if the Beeb are adopting a new internet technology, then it’s a pretty safe bet that they’ve thought things through and it has a good chance of becoming mainstream, if not already.

Podcasting

Podcasting is an obvious fit with the BBC and provides them with another useful distribution mechanism for their content, enabling people to catch up with their favourite shows at their own leisure.

Out of all of the new internet technologies, the podcast is probably the best known and most widely adopted, thanks to the ubiquitous iPod. If you’re still struggling to work out what it’s all about though, then my previous post on What is a Podcast? may shed a little light.

RSS News Feeds

RSS feeds are a very useful way of keeping up to date with your favourite websites, without having to check them all individually every day. If you’re not sure what RSS is all about, then my previous post on What is RSS? maybe just what you need.

I’ve been a proponent of RSS feeds for a long time and regularly include them in websites that I develop. While the BBC have provided RSS news feeds for a long time also (where I first encountered RSS), unfortunately RSS feeds still don’t seem to have broken through to mass adoption, despite features being included in all new web browsers allowing you to read them.

Social Media

Some people love it, some people hate it and some people just don’t get it.

I was probably in the latter category; didn’t really understand it, so couldn’t really see the point, until about a year ago when the BBC started putting a little toolbar at the bottom of every article on their news website:

I was immediately intrigued and decided to investigate, on the principle that if the BBC were adopting it, then it’s really something that I should be paying attention to if I didn’t want to get left behind.

StumbleUpon

StumbleUpon was one of the social networking/bookmarking websites that the BBC included in their new toolbar, so I took the plunge and setup my own profile on the site as an experiment.

Once you’ve set up your profile telling the system what sort of topics you are interested in, the system will suggest new websites that you may like and probably would never have discovered otherwise.

While I haven’t really done much “networking” on this site, I have found it to be an amazing resource for finding new and informative websites.

Twitter

It’s not immediately obvious that the BBC have adopted twitter, but they have. Twitter is a web service that you can use to send short messages of up to 140 characters and is touted as a micro-blogging system, although this belies its true potential.

Twitter has gained popularity because you can use it on your mobile phone with text (SMS) messages and it can also be integrated with your own websites, Facebook or your web browser.

If you subscribe to someone’s twitter feed, like the BBC for example, you can be alerted anytime they post something new. The BBC have numerous twitter feeds, which can act a bit like a personal news ticker service. Some examples of their twitter feeds are:

• BBC News – General
• BBC Business
• BBC Politics
• BBC Science
• BBC Health
• BBC Education

Into the Future

Guaranteed, things in the internet world are going to continue expanding and changing at an alarming rate. If you’re struggling to keep up with all of the latest fads on the internet, then pay the BBC a visit to see what they’re up to.

If the Beeb have adopted the latest internet offering, then it may be well worth investigating it yourself. While they may not get it right every time, they are probably heading in the right general direction.

How often have you been browsing the web when you suddenly see a little padlock symbol appear in the corner of your web browser? Well, this symbol indicates that you have entered a secure web page, but how secure is it and how does it all work?

Security is a big issue online. We’re constantly being bombarded by the media about online fraud, spam and all sorts of other nasties that we could encounter while surfing the web, almost to the point of becoming so paranoid that we won’t go online anymore.

However, there are technologies in place to try and make things a little safer. For example, whenever you enter your credit card details online, you have probably entered a special secure type of web page without realising. So what is this special type of web page, how do you know if you’re on one and how secure is it anyway?

HTTP and HTTPS

Whenever you’re surfing the web on normal web pages, you will be using a special web protocol called HTTP (HyperText Transfer Protocol).

This is just something that makes the web as we know it work. If you look at any web address or URL in your browser’s address bar, you will see that it always begins with http://, signifying that you’re using the Hypertext transfer protocol.

To help improve security on the web, the standard HTTP protocol was enhanced with an additional security layer called the Secure Socket Layer (SSL) to produce a new protocol called HTTPS (HTTP over a Secure socket layer).

Spotting a Secure Web Page

So how do you know when you’re on a web page using this secure web system?

The first method of telling if the web page you’re looking at is secure, is to look at the URL in your browser’s address bar. If the URL begins with https:// instead of http:// then you’re on a secure web page.

This is quite subtle and not many people will be aware of this difference, so most web browsers will also display a small padlock symbol somewhere to indicate that you’re on a secure web page:

Unfortunately, you can’t choose whether or not to use this secure format to view web pages, as this is decided for you by the web site you’re visiting. This secure connection is normally reserved for web pages that transmit or retrieve sensitive data, for example credit card details, and will happen automatically.

Any Port in a Storm

The internet, including web pages, sends and receives its data through things called ports. Conventional unsecured HTTP normally uses port 80. However, whenever a secure web page is used, port 443 is used instead, ensuring all secure data is processed through a completely different channel.

How it Works

Whenever you view a web page, data from the web server is sent to your browser in plain text over the internet. Likewise, if you fill in a form on that web page and  click submit, your data from the form is sent back to the web server in plain text.

When you enter a secure web page, the data sent from the web server to your computer, and more importantly, any form data (such as your credit card details) sent back to the web server is encrypted.

The upshot of this is that if anyone managed to intercept your communications over a secured web connection, then they wouldn’t be able to gain access to your information, all they’d see is gobbledygook.

How Secure is Secure

So, you now know how to spot when you’re on a secure web page, and that your data is transmitted securely, but exactly how secure is secure?

According to one computer security expert, Professor Gene Spafford (guess what, he has a beard!), the level of security on secure web page communications is analogous to:

“Using an armoured truck to transport rolls of pennies between someone on a park bench and someone doing business from a cardboard box.”

What this means is that while in transit, your sensitive data is pretty secure. However, if your PC gets compromised by some internet virus or trojan, then your sensitive data could be hijacked before it even reaches the secure web connection, and you’d probably be none the wiser until you get your next credit card bill!

Likewise, the other potential source for compromise is the receiving computer or web server. There’s really not much you can do about this other than trust that a reputable online credit card processor should have taken all reasonable precautions to secure their servers.

Any security system is only as secure as the weakest link in the chain. So it’s vitally important to make sure that your PC isn’t a weak link by installing and regularly updating anti-virus, anti-spam and firewall software.

Certificates of Trust

To help gain your trust in secure websites, website owners have an SSL certificate that is used as part of the encryption process. A reputable website will have this certificate signed by a third party, such as Verisign, to prove that they are who they say they are.

By clicking (or double clicking, depending on your web browser) the little padlock symbol in your browser on a secure web page, you can view the details of the website’s SSL certificate to confirm its authenticity and validity.

To help with your piece of mind while surfing the web, newer versions of web browsers will warn you if a certificate is not registered, or is out of date when you visit secure web pages. This is another reason for you to keep your computer updated with it’s latest security patches, so that you can benefit from these latest safety features.

Safe Surfing

So, in summary, to give you a little extra confidence when making online purchases always check for the following before entering your credit card details:

• Look for https:// at the beginning of the URL
• Look for a small padlock icon in your browser
• Click the padlock icon to check the certificate’s authentication

In stumbling around your computer’s operating system, or when setting up an internet router for your broadband access, you may have come across the term MAC address. It’s obviously pretty important for getting things talking on the internet, but what exactly is a MAC address?

Well, in computer terms, a MAC address certainly isn’t the address of your local fast food joint where you can order an oversized cheeseburger and large fries, but it is fundamental to the operation of your computer on a network.

So if you’d like to know a bit more about the ins and outs of a computer’s MAC address, rather than the contents of a McDonald’s deep fat fryer, then scroll down on your McMouse, or tap on your McKeyboard and read all about it.

Hardware Serial Numbers

The term MAC is an acronym for Media Access Control. A MAC address is also sometimes referred to as an Ethernet Hardware Address (EHA), hardware address, adapter address or physical address.

A MAC address is essentially a unique, fixed serial number of your computer’s network card in a globally agreed format. This network card can also be referred to as a Network adapter or Network Interface Card (NIC).

Globally Unique Addresses

For practical purposes, the MAC address of a computer’s network card is globally unique and fixed to the network card in the computer. If your computer has more than one network card, then each network card will have it’s own individual MAC address.

If a network card were swapped from one computer to another, then the MAC address would follow the network card to the new computer.

Network Cards and Networks

Network cards in computers are used to send data from one computer to another over a network, either via a local office network for example, known as a Local Area Network (LAN), or across an much bigger external network like the internet,  known as a Wide Area Network (or, you guessed it, a WAN).

Network cards can either use physical cables (traditionally CAT5 with standard RJ45 connectors that look a bit like big telephone connectors), or they can use wireless (WiFi for example) to transmit their data. In either case, wired or wireless, the network card will have a unique MAC address associated with it.

MAC Addresses and IP Addresses

When we configure computers to talk to each other over a network, we tend to use  IP addresses as their primary means of identification. These IP addresses are a bit like the computer equivalent of telephone numbers. If you’re not familiar with IP addresses then my previous post, interestingly titled What is an IP Address? may help.

MAC addresses are the nuts and bolts of what makes the IP addressing system work and are more fundamental to the operation of the internet and the transmission of data between machines than IP addresses, as they uniquely identify each physical data point on a network.

The relationship between an IP address and a MAC address is a bit like in a car, where the car’s registration or licence plate is like a computer’s IP address. It uniquely identifies the vehicle, but isn’t too difficult to change if required (for legitimate or illegitimate purposes). Similarly with computers, it’s quite easy to change an IP address.

A MAC address is a bit like the serial number of the vehicle’s engine. An engine is closely tied to the vehicle, although it’s serial number is not used as the vehicle’s primary identifying method. Like a MAC address, an engine’s serial number is much more difficult to change than the vehicle’s licence plate.

A further similarity with MAC addresses is that if the engine is put in a new vehicle, then the serial number follows the engine, and doesn’t stay with the old vehicle.

Wireless Security

So where are you likely to come across MAC addresses in your every day use of a computer?

Well, you’ve probably heard a lot about securing wireless networks to prevent unwanted users from piggy backing onto them and surfing for free. One way of doing this is to set up the Wireless Encryption Protocol (WEP) on your router to encrypt all of your wireless data.

Another way often offered by wireless routers is to make the router only available to known MAC addresses. To use this method you need to add a list of authorised MAC addresses to your router or broadband modem. These MAC addresses should be the addresses of the wireless network cards in the computers that you want to have access to the internet. Your wireless router should give you instructions on how to do this.

Format of a MAC Address

So, what does a MAC address look like? Well, the standard form for MAC addresses is six groups of two hexadecimal digits (characters 0 – 9 and A – F) separated by a hyphen (-) or a colon (:):

12 – 34 – 56 – 78 – 90 – AB

or

12 : 34 : 56 : 78 : 90 : AB

Discovering Your MAC Address

Unfortunately it isn’t obvious where to find your MAC address in case you need it. If you’re running a Windows PC, you can find it by going to Start, Programs, Accessories and open the Command Prompt program.

A new black window will open, in which you will need to type ipconfig /all and then press the <enter> key (see highlighted below). The window should then display a whole load of information about all of the network cards in your machine.

The MAC address for each network adapter is displayed as its physical address (see highlighted below) in this case 00-0D-88-9C-C6-59.

Room for Expansion

The MAC addressing system can cater for a pretty large number of uniquely different addresses, or to be precise:

281,474,976,710,656

That’s an awful lot of network cards, but to put this in perspective, the current estimated population of the planet is just over 6.8 billion:

6,843,400,000

This means we could all have over 41,000 computers each, with every single computer having a globally unique address on it’s network card. I just haven’t quite figured out where I’m going to put all of mine yet; perhaps Belgium…

Filling in online forms nowadays can be a bit of a mission. Not content with forcing you to fill out pages of obscure questions about your first pet etc., before allowing you to hand over your hard earned cash to buy the website’s latest offering, web hosts are now also asking you to decipher increasingly cryptic pictures of words before allowing you to continue.

Is this just a global conspiracy to test the online world’s spelling abilities, or is there a deeper, more important meaning?

Definition of CAPTCHA

As the word CAPTCHA is not one in common usage outside of bearded computer geek circles, perhaps it’s first wise to look at the derivation of the word prior to examining it’s implementations and implications.

CAPTCHA is a made up acronym for Completely Automated Public Turing test to tell Computers and Humans Apart.

Turing Test

The above definition is hopefully fairly self explanatory apart from bit about the Turing Test. This is obviously fundamental to what CAPTCHA is all about, so what is a Turing Test?

The Turing Test was developed in 1950 by the British computer scientist Alan Turing (sometimes referred to as the father of modern computing) and was designed to test a computer’s ability to demonstrate intelligence, or not, as the case may be.

Putting this together with the definition of CAPTCHA above, we should now have a working understanding of what CAPTCHA is; essentially a computer generated test to check that the response has been supplied by a human and NOT another computer.

These automatic tests work on the basic principle that computers are intrinsically stupid, they just do exactly what they’re told and can’t think for themselves.

As such a CAPTCHA test is a simple challenge and response test, where the website’s computer server asks the user a question (the challenge) to which a valid answer (the response) is required before the user is allowed to proceed.

The key factor in this being that the sort of question asked must not easily be guessed or worked out by another computer system, indicating that the response must have come from a human.

Anti-Spam

So why do we need these CAPTCHA tests whenever we’re asked to complete an online form?

Well, unfortunately some people out there have ulterior motives and set up automated computer systems (called bots) to logon to websites, creating bogus accounts to promote their dubious products or activities; commonly referred to as SPAM.

By implementing these CAPTCHA tests, these spam bots can be stopped in their tracks at the first hurdle.

Cryptic Pictures

While CAPTCHA tests can take on many forms, by far the most common is the cryptic picture, where a distorted image of a series of characters is presented to you and you are asked to enter the characters you see in the box provided.

The computer system asking the question knows what characters it displayed, so can match your answer accordingly. If you get it correct, you are allowed to proceed, collecting £200 if you pass go!

While recognising deformed characters is fairly straightforward to us mere mortals, fortunately computers struggle with this, thus providing us with a useful weapon against the spammers.

Audio CAPTCHA

While most CAPTCHA systems rely on visual clues, some now also utilise audio CAPTCHAs, where you listen to a spoken audio recording with background noise and are asked to type in the characters you hear.

This type of system is a useful addition to the standard visual CAPTCHA systems, enabling visually impaired users equal accessibility to the websites in question.

A good example of this type of accessible an CAPTCHA system (image shown above) can be found at www.captcha.net.

Ongoing Battle

While it may be a pain in the backside to answer these CAPTCHA questions when you have to fill in online forms, unfortunately it’s become a necessary evil in the constant battle against spam.

Think of it this way, every time you answer a CAPTCHA question, you’re reaffirming your supremacy over those dumb computers and helping in the battle against spam!

While the term URL may not be familiar to everyone, the chances are that you use them everyday without knowing, as a URL is essentially just a web address. But what do all the different parts of a URL actually mean?

URLs are things we use every day in our general surfing of the web, but they are something that many of us will never stop to think about too much.

So partly in response to a request left in a comment from a reader, Joebunny, and partly as a prelude to a forthcoming post that will require a general understanding of URLs, I hope to explain, without going into too much detail, what a URL is all about.

URLs and Web Addresses

For those of you not familiar with the term URL, it’s really just geek speak for an address pointing to an internet resource, where such resources can be a web page, e-mail account or file server for example.

The term URL is actually an acronym for Uniform Resource Locator, i.e. a standard way for finding/addressing resources on the internet. The most common type of URL encountered, and probably most familiar, is a web address, and is the one that I’ll focus on in this article.

Anatomy of a Web Address

Most of you should be pretty familiar with the format of an average web address, for example (excuse the shameless plug):

http://www.richardfarrar.com/archives/

If we break up the above URL into its component parts, we can see how common web addresses are constructed and which parts are important:

http://

This is the first component at the header of every URL and is called the scheme. This component tells us what type of internet resource we are looking for e.g. a web site or file server. In this example, http:// tells us, and the web browser, that we are looking for a web page.

For the uber geeks amongst you, http stands for Hyper Text Transfer Protocol, although that’s not really important to the present discussion. However, this is an important part of a web address and has to be included for everything to work properly.

If you type a web address into most web browsers without the http://, the web browser will automatically add it for you. So while it’s a critical part of the web address from the technical nuts and bolts point of view, it’s a bit superfluous when you’re quoting a web address to someone.

Examples of some common URL schemes are:

• http – Hyper Text Transfer Protocol (web page)
• https – Secure HTTP (secure web page, e.g. online banking)
• ftp – File Transfer Protocol (file servers)
• mailto – E-mail address

www.

Pretty much most web addresses will be prefixed by WWW , which stands for World Wide Web, indicating that the URL is for a website. However, unlike the http:// component, this is not a technical requirement of a URL.

By way of example, the BBC’s news website does not use the www component:

http://news.bbc.co.uk/

If you tried adding www to the above web address, it wouldn’t work. So while the www is an important part of the actual address,  it isn’t a fundamental part of a URL.

In the above example the news part of the web address is called the sub domain, where bbc.co.uk is called the domain (more on this in a moment).

If a website domain were to be considered as a filing cabinet containing loads of web pages, then a sub domain could be considered as a draw in the filing cabinet containing web pages specifically about the sub domain or specific topic, news in the above example.

Out of interest, while the majority of website addresses are prefixed by the www component, you will often find that if it’s missed off, the web address will still work. For example try the following with the missing www:

http://richardfarrar.com/archives/

Still works? Well it did when I checked it…

richardfarrar.com/

This part of the web address is called the domain name. If nothing else is typed in after this it will take you to the website’s homepage.

A domain usually consists of a chosen name, richardfarrar in this example, which is called the second level domain, followed by one or more defined top level domains (TLD), .com in this example.

Top level domains are defined by international internet organisations, with certain TLDs only being allowed to be used by certain organisations.

Examples of top level domains are:

• .net – intended for network providers
• .org – organisations not matching other top level domains 
• .gov – government departments
• .mil – military organisations
• .edu – educational organisations
• .info – intended for informational websites
• .biz -for use by businesses

Some top level domains also include a following country code, which are reserved for countries and independent territories, examples of which are:

• .uk – United Kingdom
• .ca – Canada
• .de – Germany
• .za – South Africa

archives/

This is the final component of the website URL, which can lead you deep into the bowels of the website and may vary from a simple page or directory like the above, to pages buried deep within the website with horrendously long addresses.

Expanding Internet

While the above list of top level domains only contains a few examples of those currently available, the size a this list is soon set to explode with recent changes announced by the regulating internet authority (ICANN) that relax the rules for top level domains, so keep your eye out for some fancy new web addresses in the future!

Hopefully that describes the basics of a web URL, so next time you type in a web address you’ll have a pretty good idea what it all means.

Until the mid 1980s, commercially purchased music was always in analogue format, be it typically vinyl or cassette. In late 1982, the arrival of the now ubiquitous compact disc (CD), co-developed by Sony and Philips, changed all that and revolutionised how we listen to music.

Digitisation

In order to create digital recordings such as CDs, the conventional analogue audio first has to be digitised. The process of digitisation takes the original audio source and chops it up into lots of thin slices. Each slice represents the volume of the audio source for a particular point in time. A digital number then stores the volume level of this slice on the CD. Each slice, or sample as it’s actually called, represents the level of the audio for a mere 23µs (23 millionths of a second).

To reconstitute the audio track, all of these samples are stuck together and the volume level of each sample is sent out to your speakers every 23µs (in the case of CDs). It’s a bit like slicing a loaf of bread and then squeezing all of the slices of bread together again to make it look like the original loaf. Not perfect, but if you squint, you’d never know that difference. CDs are very similar, because the slices are so thin, you don’t know the difference.

Sample Rate

The rate at which we take the samples and replay them is called the sample rate. For CDs, 44,100 samples are taken every second! Now, because we have to store the value of every sample, it follows that higher sample rates would require a lot more storage, which can become a problem. Conversely, a higher sample rate directly equates to a more accurate representation of the original signal, and therefore better audio quality. So, ultimately compromises have to be made and a 44,100 sample rate was deemed to be a sensible compromise when CDs were developed.

Bit Rate

Now we have an overview of sample rates, we are in a good position to discuss bit rates, as the two are inextricably linked. Each sample we discussed above is represented by a digital number and every digital number is made of digital bits; there’s the magic link! A bit is a single digit, either a one (1) or zero (0). In the case of our CD, each digital number comprises 16 bits, which allows numbers up to 65,563 to be stored; over 65,000 different volume levels!

As we have two ears, we need to store two sets of samples, one for each ear; stereo.

So, to calculate the bit rate for CD audio, we multiply our sample rate (44,100) by 2 (for stereo) and by 16 (the number of bits in our digital numbers):

44,100 x 2 x 16 = 1,411,200 bits per second (bps) = 1,411 kbps

We have now calculated the bit rate for the standard CD, which turns out to be 1,411 kbps.

Compression

If we used a 1 GB MP3 player to store music at the above bit rate for example, we would only be able to store 100 minutes of music; not very much! This is why MP3 was invented, as a way of reducing the amount of space that music needs when stored on a computer or music player by squashing, or compressing, the original CD audio data to save space. There are numerous compression systems available, with MP3 being the most popular, but they all aim to provide the same result; significantly reduce the audio file size.

How the compression works is somewhat beyond the scope of this article, as it uses a lot of complicated mathematics to work out which bits of the music we can hear, and which bits we can’t. Essentially it saves space by not bothering to store the bits of the music that we can’t hear. For example, if you have a Heavy metal band playing with the volume turned up to 11 and someone at the back of the stage taps on a triangle, you are unlikely to hear it. So MP3 decides that the tour bus is too full and fires the triangle player, saving space and reducing the queue to the bathroom at the same time!

During this compression process, typically 90% of the data is thrown away, leaving file sizes about one tenth of the original size, which in turn means that your MP3 player (or iPod for the image conscious types) is able to store ten times the number of songs compared to if it had to store the original uncompressed CD data.

Bit Rate Versus Quality

Now that we have reduced our file size to approximately one tenth of its original size, we only have one tenth the number of samples and so consequently only have to send them out to our speaker system at one tenth the original rate, i.e. our bit rate is ten times slower. A typical bit rate for good audio quality would be around 128 kbps (kilo bits per second, or thousand bits per second), approximately one tenth of the bit rate for the standard CD.

Unfortunately compression system have limitations, the more data they throw away, the smaller the file size, the lower the bit rate, but the worse the audio quality, or to use the band analogy above, more and more members of the band get thrown off the bus, so there are less musicians to make the music.

So, we should now have an understanding of what bit rates are and their direct correlation with audio quality. As a useful guide line for the quality of different bit rates:

• 320 kbps – Almost indistinguishable from the original CD
  
• 128 kbps – Reasonable audio quality, typical for MP3s
• 64 kbps – Not recommended for music, but good for speech
• 32 kbps – Poor, often used to reduce web download times

Hear for Yourself

If you’d like to hear for yourself the direct effect of bit rates on audio quality, check out the following demonstration MP3 tracks, courtesy of Silicon Bay:

• 128 kbps MP3 – MP3 track recorded at 128 kbps (92kB)
• 64 kbps MP3 – MP3 track recorded at 64 kbps (43kB)
• 32 kbps MP3 – MP3 track recorded at 32 kbps (22kB)

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