GNU GPL
The license under which the WordPress software is released is the GPLv2 (or later) from the Free Software Foundation. A copy of the license is included with every copy of WordPress, but you can also read the text of the license here.
Still lost? We have a beginner’s GPL primer, too.
Third Party Libraries
Third-Party libraries must be GPLv2 compatible, but retain their own copyright.
Contributor Copyright
As a contributor, you retain the copyright to your code, however by submitting it to TracTrac An open source project by Edgewall Software that serves as a bug tracker and project management tool for WordPress. you are releasing it under the GPLv2.
