Open Source

Open Source is... well...what is open source exactly? It's the Philosophy of free software. The thing about it is that it's free as in freedom, not free as in free lunch. Most open source software is released under the GPL. Basically the GPL states that anyone can see/edit/change the code, so long as they allow other people to see their code.

For example, you can see the source code for linux. You can change the source code for linux any way you want. However, you are required to allow people to see and change any of the changes you made. It's very simple, and many people like the idea. Even some companies use open source software in their product. Companies such as


Another one of the most common open source licenses is the Mozilla Public License.

***NOTE*** The GPL and MPL are legal documents and I am not a lawyer, and I do not represent either entity. I have no experience with copyright law, nor do I have any legal training. I do not want anyone to use the descriptions given here in a court of law, nor can I be held responsible.
Phew! Now that that's out of the way...


Mozilla Public License(MPL)

General Public License(GPL)
Under the MPL, you cannot re-release the source code under a
license that imposes restrictions that are not in the MPL. You may
use a proprietary license under the MPL Larger Works License
(e.g. Flash player) 		The GPL does not allow you to re-release the code under a
license that imposes restrictions or takes away rights specified
in the GPL. Thus, you cannot change the license from the MPL to the GPL

Any binaries with source code under the MPL can be released under
a different license in binary form.
Any binary under the GPL must be released under the GPL. You cannot
release a GPL binary under a different licensce.

Any code added to code under the MPL can be released a under a different
license.
Any code added to a program released under the GPL must remain GPL, and
cannot be released under a different license provided you distribute
it. If you are not distributing, and are using the code for you own personal
use, you may use any license you want.