Summary of everything

WHY IS WORDPRESS LICENSED UNDER THE GPL?
Why People Hate the GPL?
What the GPL Means to You?
The GPL and WordPress?
WordPress’s GPL Requirement?
Non-GPL WordPress Themes & Plugins?
How WordPress Plugin and Theme Developers Make Money?
THE LEGAL POWER OF THE GPL?
REDUCED RISK OF LEGAL ACTION?
HOW THE GPL WORKS IN FAVOR OF WORDPRESS END USERS AND DEVELOPERS?
ANY REASONS WHY YOU SHOULD ADOPT THE GPL LICENSE?
What is Split Licensing and the GPL?
If I modify the core WordPress software or a GPL’d theme or plugin, must I release the source code of the modified versions(s) to the public?