3. Open source software

With open source, the source code itself is available to the public. Anyone with the right skills can compile the source code to create the application's executable file. The source code is free.

People may make their software open source either out of a sense of altruism. Or perhaps they want their work to be used by as many people as possible. Alternatively it may be because they want to make it possible for others to collaborate and build upon what they have created.

Many licences have been developed to support open source distribution. For example the GNU General Public Licence in summary is shown below

You may copy, distribute and modify the software as long as you track changes/dates in source files. Any modifications to or software including (via compiler) GPL-licensed code must also be made available under the GPL along with build & install instructions.

So if you modify the source code then that version also has to be made available under the GNU licence.

Open source code is written by volunteers - experts in their field who want to make their code available. Just like their commercial counterparts, they need somewhere to work together online, and so services such as SourceForge provide a centralised online environment to support open-source projects. GitHub is also very popular depository of projects.

Here are some examples of open source software

• GIMP - a photo editing application
• Open Office - an office suite with word processor, spreadsheet and database
• Audacity - an audio recording and editing application
• Linux - operating system