All of the useful applications we can use for FREE?
The next question is understandably, how is this possible? The answer is the WordPress is an open source software licensed under GPL. So let’s answer two questions:
What is open source?
OpenSource.org defines this as software as one that can be freely used, changed, shared by users, and distributed under a license that conforms to the open source definition.
What is GPL?
The free software foundation (gnu.org) declares that users should not be restricted by their software and defines 4 specific freedoms (1) to use software for any purpose (2) to change the software to suit your needs (3) to share the software as you see fit; and finally (4) to freely share any changes you make to the software.
Read more about GPL ong the GNU Web site.