The Linux® license is a legally enforcable software license known as the general public license. Its main provisions are meant to protect the freedom to use open source software created on the Linux® platform and the individuals who use it. There are many different aspects of the Linux® license but the main one is that software can be modified and remodified by other users without legal consequences. The idea is known as copyleft.
Although the Linux® license protects open source software from copyright regulations, software designers operating under the general public license may still charge a fee for their software. Copyleft does not require that any variation of the original program be given away for free, but it does prohibit anyone from claiming exclusive rights to the program. If another software designer modifies and sells the updated version, that would be legal. The original creator cannot prosecute for copyright infringements because the software was created under the general public license.
One of the ways the Linux® license enforces copyleft is by requiring that the source code, or programming information used to create the software, be included with the software itself. If it is not included in the software, it must be readily available on the Internet. As long as the location is clearly detailed and accessible to the user, it complies with the Linux® license. Another requirement of the Linux® license is that a copy of the general public license must accompany the software. This is so the next user or software modifier can read and understand the rights and limitations should he or she decide to modify the software.
These two requirements of the Linux® license — supplying the source code and including the general public license — are only applicable if a user modifies the software with the intent to redistribute the product. If a user makes changes to the source code for his or her own personal use and does not redistribute it, there is no requirement to follow the provisions of the general public license.
Users who do not abide by the general public license can be sued by the original software designer who wrote the program under the Linux® license. Many court cases have upheld the general public license. The Linux Foundation, an organization dedicated to supporting the Linux® platform, created a program to help software designers understand and create open source software. This program checks source code input by users to make sure it abides by the rules of the general public license.