Open Source Software Licenses
From Linux 101, The beginner's guide to all things Linux.
Contents |
[edit] The Basics
Open Source software is protected by copyright law, just as closed source software and music is. It is what gives the legal backing to enforce the stipulations imposed by the license software uses. If they were not valid, then people could use open source software with disregard to the author's wishes.
[edit] The GNU Licenses
The GNU licenses are probably the most common, at least in the Linux community.
[edit] GPL
The GPL, or General Public License, is used by software such as the Linux kernel, Qt, and thousands of others. The license imposes the following restrictions:
- If you distribute a binary outside of your organization, then any changes you made to the original source code must be made available upon request.
- A nominal fee may be charged for source code requests.
- All derivative works (such as linking to a GPL library) must be licensed under the GPL.
These are the basic premises of the GPL. If you give your binary out, then you are under obligation to allow others access to the source code. However, some fail to realize that companies may use GPL software inside their company and modify it without obligation to release their changes to the public.
It is important for software developers to keep in mind what license a library uses if they are linking against it. This is why some claim Qt is "less" free than Gtk+, which is licensed under the LGPL. Those who do not purchase a commercial license of Qt must license programs they write utilizing the Qt libraries as GPL.
[edit] LGPL
The LGPL, or Lesser General Public License, is less restrictive than the GPL. Software such as Gtk+ is licensed under the LGPL. This means developers may write closed source software that uses the Gtk+ libraries. The only restriction is that if they make and distribute changes to the Gtk+ source code, then they must make those changes available. But their own software may stay closed sourced. This results in a potentially wider audience to use the software, while insuring that any improvements made to it stay open source.
[edit] The BSD Licenses
The BSD licenses are the least restrictive of the bunch. This is why Windows is able to use BSD code in their products. All that is required is that the copyright statement remain intact. See below for more information.
