The main spirit of the GNU Project's General Public License is the spirit of free use, free code sharing, preventing patent abuse, and maintaining free software.
1. Free use: GPL requires that licensees can freely use, copy, disseminate, and modify the software, and can redistribute the modified code. This right of free use is at the heart of the GPL.
2. ***Shared code: GPL stipulates that software using GPL license must disclose the source code, and anyone can view and modify the code. The idea is to encourage developers to learn from each other and collaborate.
3. Prevent patent abuse: GPL also stipulates that if the software using the GPL license involves a patent, then the patent must be authorized to all users, not only to a specific user or organization. The purpose of this is to prevent certain people or organizations from using patents to restrict the use and modification of software.
4. Maintain the spirit of free software: GPL hopes to promote the development and popularization of free software by emphasizing the principles of free use and maximum sharing of code. It also hopes to protect the spirit of free software and prevent it from being Commercialization or privatization.