There can't be many people who haven't heard of Linux. In short, it's an operating system just like Windows but, unlike Windows, you won't find it on many PCs you buy from the high street or from computer magazines.

The reason for its popularity is threefold. First, most versions of Linux (of which more later) are free; second, anyone can modify it to suit their needs; and third, it runs well on low-specification computers.

Linux has a reputation as an operating system for high-end purposes such as web servers, and high-end users such as programmers.

It is also seldom out of the news, appearing in devices as diverse as the PlayStation2 and Xbox, and on 60,000 desktop computers in the West Yorkshire police force.

IBM actively promotes Linux to big companies and even Microsoft acknowledges that "Linux is a serious competitor".

So what is Linux exactly, and how does it relate to the average home or office computer user? More importantly, is it as friendly as its penguin mascot suggests?

In this feature, we'll be reporting on the background and history of Linux, and showing you how it looks and works. If you fancy having a go, we'll also be telling you how to get it and install it, and how to find your way around it.

The ins and outs
The Linux story starts in the early 1970s when AT&T's Bell Labs developed an operating system called Unix for the mainframe computers of that era.

Unix rapidly became an industry standard, with companies such as Sun Microsystems and DEC writing their own versions.

In 1983, Richard Stallman, a programmer at the Massachusetts Institute of Technology, founded the GNU project. This stood for 'Gnu's Not Unix' and his aim was to combat the increasingly commercialised versions of Unix with a freely available version created by volunteers and enthusiasts from around the world.

The terms of the Gnu Public Licence (GPL) ensured that, unlike commercially produced software, GNU would be open to inspection, modification and improvement by anyone and everyone.

By 1991, thanks to the personal computer's popularity, computing was no longer the prerogative of big businesses and academic institutions.

This prompted a Finnish student, Linus Torvalds, to embark on creating a version of Unix that would run on a standard PC rather than a costly mainframe computer.

Thus was born 'Linux', named after its creator but also following the GNU tradition of wordplay. The name also stands for 'Linux Is Not UniX'

Torvalds' principal achievement was the creation of a 'kernel', the core of an operating system which is responsible for making all the parts of a computer work together.

By itself, however, it isn't much use as it doesn't provide any way for a user to interact with it. For that there needs to be something called a 'shell'.

Unix used the 'Bourne' shell; the GNU programmers came up with BASH - the 'Bourne Again SHell'.

While many Linux users are happy with BASH, the fact that it only allows text-based commands to be typed on a keyboard is a bit of a deterrent and so the final piece of the Linux jigsaw is the 'user interface' or UI.

There is range of different Linux UIs available and the best offer the same set of features as Windows. The two leaders in the UI field are GNOME and KDE and we'll be looking at both of these later.

Get it on
So where can you get a copy of Linux? Just because Linux is free, it doesn't mean you can't buy it. Conversely, the GPL doesn't stop companies making money out of Linux by selling copies on CD-Rom.

Such companies often offer added value, such as printed manuals, technical support and training. There are many such distributors, including Red Hat, Mandrake, SuSe, Slackware, Debian, Xandros (formerly Corel Linux) and Lindows.

The various versions of Linux are also known as 'distributions'. At the time of writing, Amazon was offering Red Hat 8 Personal for around £32. This features seven CDs containing the operating system, applications and documentation, as well as a printed manual and 30 days' technical support.

Various other versions can be ordered from the distributors' websites (see below).

You can get other Linux distributions for much less. BuyLinuxNow.co.uk, for instance, offers Mandrake Linux on CD-Rom for just £4.

If you'd rather spend money than effort, then you can buy an entry-level PC with Lindows pre-installed from as little as £250, excluding a monitor.

If you'd like to get Linux free, you can download it from lots of different places. Bear in mind, though, that this will involve a long wait. Even with a broadband connection, downloading a 600MB file can take a good few hours.

If you can't manage the download, there is still a solution. Unlike Windows, you're free to install most versions of Linux on more than one PC so it's perfectly legal to borrow a disc from a friend.

Separate lives
So you've got a Linux installation disc, now what? First, you need to make room for it on your hard disk and, once again, there's a trade off between effort and expense.

Assuming you want to retain Windows on your PC, the simplest thing would be to buy a new hard disk, configure this as a 'slave' and install Linux on the new disk.

Alternatively, you can give Linux an existing partition on your hard disk or use the spare space on an existing partition.