There have been many attempts on the net to do a taxonomy of various software licenses, but all of them have been pretty complex for the average person trying to comprehend the meanings. Here is an attempt to simplify.
The following ideas are roughly in chronological order and in many cases they're an attempt to change a previously established model, deemed unsuitable for some specific purposes.
This, along with Commercial, closed source software is one of the most well understood ideas. It's not owned by anyone, free for all, for any purpose.
All rights belong to the entity that developed the software, or the one it has been sold to. End users "license" the software and have minimal necessary rights to use it.
This is very similar to public domain. But in litiguous societies in developed world, people wanted liability protection from lawsuits and protection against plaguiarism or misrepresentation of the work.
The main intent of this license is to guarantee that the user of such software has the same rights (GPL software rights) to all software, that incorporates GPL licensed software.
In other words, it's mainly about the rights and freedom of the user of software. The origin of this license is in the blurring of the distinction between the user and developer of the software, typically in a university or a technology enthusiast setting.
While relying on intellectual property (IP) laws for its enforcement, the main intent here is to invalidate the idea of intellectual property, as practiced by Commercial closed source folks.
Mixing GPL with other classes of software, meant the loss of rights to the developer, while favoring the end user. In a world dominated by commercial software, this was a significant hinderance to the adoption of GPL licensed software.
LGPL, initially known as library GPL, was an attempt to moderate the self-propagating effects of GPL. Mozilla public license (MPL) is similar in nature.
There have been many attempts to serve the needs of a company/developer, while providing some extra benefits/rights to the end user, compared to closed source commercial software. But none of them have reached a critical mass compared to the previous class of licenses.
| Public Domain | Closed source | BSD style | GPL | MPL/LGPL | |
| Developer | Donation | Profit/Livelihood |
Donation with legal protection and donor recognition | Desire to revamp the IP based system | Same as GPL with concessions and recognition of others IP |
| End User | Cost savings, but no gurantees on derivatives | Least beneficial | Same as Public Domain | Cost savings, with guaranteed rights on derivatives |
Cost savings, with guaranteed bug fixes |
| DIY End User | Can fix my own software, but no rights to others' bug fixes | No rights. | Same as Public Domain | Can fix my own software, with rights to others' enhancements and bug fixes |
Same as GPL with concessions and recognition of others IP |
| Entrepreneur | Software that can be used in my next venture without limits | The most proven model to be profitable and deemed necessary for the survival of most software companies |
Same as Public Domain | Useful to get developer mindshare/marketshare, while preventing other companies from leveraging IP. | Useful to get developer mindshare/marketshare, while guarateeing bugfixes and preventing embrance-and-extend |
The highlighted elements best serve the interests of a person, if she belongs exclusively to one of the user categories, in the author's opinion. However, life is never so simple and many belong to multiple categories above.
It is the hope of the author that this article provides a good frame of reference, in qualifying phrases such as "freedom", "better license" etc, by making people think about "whose freedom ?" and "better in what sense ?".