44 7. BUILDING FOR FREEDOM: OPEN DATA, OPEN SOURCE
Stallman later clarified that free software was software that guaranteed users four freedoms:
0. The freedom to run the program, for any purpose.
1. The freedom to study how the program works, and adapt it to your needs. (Source code is a requirement for this.)
2. The freedom to redistribute copies so you can help your neighbor.
3. The freedom to improve the program, and release your improvements to the public, so that the whole community benefits.
(Again, source code is a requirement for this.) “I consider that the golden rule requires that if I like a program I must share it with other people who like it. I cannot in good conscience sign a nondisclosure agreement or a software license agreement. So that I can continue to use computers without violating my principles, I have decided to put together a sufficient body of free software so that I will be able to get along without any software that is not free.”
Stallman codified these freedoms in the GNU General Public License or GPL. If you modify a piece of software that is licensed under the GPL and redistribute it, the license requires that you also redistribute the source code at no extra charge and allow everyone who receives a copy to do likewise.
Since 1984, the GNU operating system (whose most popular flavor is GNU/Linux) has been built and released under the GPL. A 2007 study found that 13% of servers and 1% of desktops were sold running GNU/Linux. And anyone can download the entire operating system for free off the Internet.
The success of GNU/Linux has led to a larger free software movement as well as the “open source” movement, which releases software and its source code under copyright licenses that provide some of the software freedoms.
The Mozilla Firefox browser, for example, is open source and currently makes up around 15% of market. Large portions of the Mac OS X operating system are also open source, including WebKit, the core of Safari, the Mac OS X web browser.
The open source and free software movements have now built free alternatives for just about every major type of computer application, from word processing to video games. And for a time it seemed like Stallman’s dream had come true: one could truly continue to use computers without having laws restrict one’s freedom—it was possible “to get along without any software that is not free.”
