WordPress Software falls under the GPL that is General Public User License focusing on Open Source App/Software Development tools.

Here are the freedoms under the GPL:

  1. Freedom to run the program for any purpose.
  2. Freedom to study how the program works and to change it, so it performs computing as you wish.
  3. Freedom to redistribute copies, so you can help your neighbor.
  4. Freedom to distribute copies of your modified versions, giving the community a chance to benefit from your changes.

Read More about GPL here: