Open source software != Free software
It’s easy for people to make the mistake of calling products like Chrome and Android “free software”, because, well... they didn’t pay anything for them. There is a very important distinction between “open source” and “free software”. Both are very specific terms that can mean completely different things, and it’s important to understand this because sometimes we start using software that advertises itself as open rather than free.
Open source
Open source means that the source code for the program is open for anyone to see. It makes no promises that you can actually do anything with it, but it at least guarantees you can see it. This provides some of the same advantages of the free software model; namely the ability to learn from the code and being able to independently audit code for stability and security purposes.
Free software
The GPL (General Public License) is the best example of a free software license, it’s the license Linus Torvalds used to release his operating system kernel, Linux, which was able to be easily combined with the GNU operating system components because they were both using the same license. This gave birth to what we now know as “Linux”, I know, though purists will be quick to mention the proper term is “GNU/Linux”.
A big misconception about the GPL is that it’s an “open source” license. Yes, the source code for a program released under the GPL must be available to all, but that isn’t all GPL guarantees to the user. The GPL guarantees what the Free Software Foundation likes to call the “Four Freedoms”:
- The freedom to run the program, for any purpose.
- The freedom to study how the program works, and change it.
- The freedom to redistribute copies so you can help your neighbor.
- The freedom to distribute copies of your modified versions to others.
From the almighty Four Freedoms we can see that the GPL guarantees much more than just simply see the source code, which is all that “open source” means. The GPL gives you the ability to modify the source, and then redistribute that modified version however you wish.
Another big misconception, and the reason so many people are confused in the first place, is the assumption that the “free” in free software is referring to free in the monetary sense. Actually, nowhere in the GPL states the developer is not able to make money off of his program or charge a fee for various services (installation, support, modification, etc). The simplest explanation out there is that free software is “Free as in speech, not free as in beer”.