Ebook: Free Software, Free Society: Selected Essays of Richard M. Stallman

This is the book to read to learn about the roots, the history of the Free Software movement started by Richard Stallman in the early 1980's.
Here in a single book are explained all the major principles of Free software. Also you can find the history of the GNU General Public license or GNU GPL for short. This is the most widely used free software license.

The origin of the GNU operating system and its variant the GNU/Linux operating system is also covered.

The importance of the Free software movement can not be overstated.
It is the Free software movement and its leading organization the Free Software Foundation that inspired other groups that have its origins in it such as the "Open source" movement.
The books explains the effects of copyright laws and patent law on innovation and society.

A must read. I fully recommend it.