[Shenzhen] Yuanchuang Association: On May 26, we will wait for you in the hall "
Among the various licenses used by free software, the General Public License (GPL) is perhaps the most noticeable.
GPL, like other free software licenses, allows the public the freedom to run and copy software, distribute and disseminate software, obtain software source code, improve software and distribute and disseminate the improved version to the public.
The GPL also stipulates that as long as the modified text as a whole or some part of it comes from the procedure following the GPL, the whole of the modified text must be circulated in accordance with the GPL, not only the source code of the modified text must be disclosed to the public, but also the circulation of the modified text is not allowed to attach restrictions made by the modifier himself. Therefore, a program that follows GPL circulation cannot be merged with non free software. The circulation rule expressed by GPL is called copyleft, which means that it is "different" from the concept of copyright.
The main principles of GPL protocol:
1. Ensure that the software is released in the form of open source code from beginning to end, and protect the development achievements from being stolen for commercial sale. Any set of software, as long as it uses the source program of third-party software protected by GPL protocol and releases it to non developers, will automatically become an entity protected and constrained by GPL. In other words, it must open source code at this time.
2. GPL is roughly a reflection of the left copyright (or "copyright", "copyright belongs to the left", "copyright does not exist", "copyright responsibility", etc.). You can remove all copyright information of the original, as long as you keep open source, and attach the GPL license with the source code and binary version, so that future generations can clearly know the licensing information of this software. The essence of GPL is that as long as the software is completely open source, the user can get the space to play freely as far as possible, so that the software can develop faster and better.
3. No matter what form the software is released, the source code must be attached at the same time. For example, if downloading is provided on the Web, the source code download link must be clearly provided on the same page where the binary version (if any) is downloaded. If it is released in the form of CD, the CD of the source file must be attached at the same time.
4. Companies or individuals that develop or maintain software developed under the GPL protocol can charge users a certain service fee. But it is still an old saying that the complete source code of the software must be provided free of charge, and the source code must not be bundled with the service or sold in any disguised form.
Introduction to more open source protocols
