Free software and source code
There is a lot of free software available. Some is software that can be used and altered without restrictions.
In some cases, software distributed as free software and then altered to have new functionality, must also allow their changes to be available on a free basis.
The free software movement was set up by Richard Stallman in 1983. He then went on to create the Free Software Foundation in 1983.
Free software licenses
Free software licenses must allow other people to use the source code themselves, and enforce the concept that there no built in elements are added that stop the software being free, or require payments to be made to use the 'free' software.
There are various licences under which free software is distributed. These include:
- the GNU General Public License
- the GNU Lesser General Public License
- the BSD License
- the Mozilla Public License
- the MIT License
- the Apache License