Linux is not a programme it's an operating system kernel and a philosophy.

Linux is a free Unix-type operating system originally created by Linus Torvalds with the assistance of developers around the world. Developed under the GNU General Public License, the source code for Linux is freely available to everyone. The operating system is causing a revolution in the world of computers.

The Linux operating system will run on most PCs including Macs. About 6% of the worlds PCs run Linux, and the proportion is growing. There are more image manipulation programmes available for Linux than there are for Windows and Mac combined.
They offer greater flexibility and equal potential to create high quality results. There are no compatibilty issues with other operating systems. Images created on Linux systems can be saved in all the common file formats.

Linux is the operating system installed on 100% of the worlds most 500 powerful computers.
Google uses a version of Ubuntu internally nicknamed Goobuntu.
Germany has announced that 560,000 students in 33 universities will migrate to Linux.
IBM does extensive development work for Linux and also uses it on desktops and servers internally.
DreamWorks Animation has been using Linux since 2001, and has more than 1,000 Linux desktops and 3,000 Linux servers.
Wikipedia moved to running its servers on Ubuntu Linux in late 2008.
NASA has switched the International Space Station laptops to Debian Linux.
Both CERN and Fermilab use Scientific Linux in all their work; this includes running the Large Hadron Collider or the Dark Energy Camera or the 20,000 internal servers of CERN
Brazil has 35 million students in over 50,000 schools using computers all running Linux

You can buy a 6ghz dual core computer with 8gb ram, 1000gb hard disk, dvd-rw and 21 inch ips monitor - running Linux with Gimp for around £200. A Windows computer running Photoshop will cost £1000 and a similar spec Mac will cost £1800

I design and work on PCs running The Universody Linux remix.
The programmes used for this site are Bluefish for the HTML and Gimp for the imaging. As with most Linux software both are free programmes distributed under the OSS (Open Source Software) program covered by the GPL license.

Stephen Fry introduces you to free software - from 2008