ZDNet: Know your rights (regarding open source software) [licensing quick guide]Sep 20, 2000, 17:07 (5 Talkback[s])
(Other stories by Michael Barr)
"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."