“One of the more confusing aspects of the open source phenomenon
is the proliferation of different source code licensing schemes.
If you are considering using software developed by others
within your products, you’ll probably want to have an intellectual
property lawyer read the individual license agreements in detail
and summarize your rights. However, this quick guide to the
licensing terminology should be enough to get you
started.”
“Free software… is all about access to the source code. The
free software movement (www.fsf.org) is as much a political
organization as anything else. Under the free software licensing
model, it is your right to use the software, modify it, and
redistribute it in any way you like. It’s even okay for you to
charge for your distribution. However, these broad rights are
conditioned upon your commitment to provide similar access to your
modifications and to never narrow the licensing rights as a
condition of distribution.”
“GPL is a specific implementation of copyleft. This is analogous
to copyright law, in which there is a general right that is
implemented in various ways in different contracts and print and
electronic publications. GPL prohibits proprietary patents related
to modifications of the software, prohibits royalties, and requires
that the same terms be attached when redistributing the software or
a derivative of it. Of course, anyone can create software and then
license it under these same terms. Use of the GPL language is not
restricted to GNU-related projects. (Their copyleft is not
copyrighted.)”
“Lesser General Public License (LGPL)… is used to license free
software so that it can be incorporated into both free software and
proprietary software. In other words, it is a weaker sibling of
GPL. The rules are basically the same, with one major exception:
the requirement that you open up the source code to your own
extensions to the software is removed. So while LGPL components
remain free software, they can be included within a larger
proprietary software package.”