So please, whenever possible, try to fill the Copying-Policy field with one of the values in the table below. If your software has parts covred by different licenses, list the most restrictive license. The codes are listed from least restrictive to most (GPL's restrictions on how you can combine GPLed and non-GPLed code explain its low place on the list).
We would prefer you not put special restrictions on commercial use. These make life difficult for CD-ROM distributors, prevent Linux from spreading as fast as it could, and confuse everybody. If you want to get paid for your effort, fine, sell your software. If you want to write free stuff, please make it free or shareware for everybody.
Placed in public domain by J. Random Hacker, 1997. Share and enjoy!If you do this, you are surrendering your copyright. Anyone can do anything they like with any part of the text. It doesn't get any freer than this. Very little free software is actually placed in the public domain, On Sunsite in mid-1997, only 3% of over 2600 software packages and documents announced PD status.
Who counts as an author can be very complicated, especially for software that has been worked on by many hands. This is why licenses are important. By setting out the terms under which material can be used, they grant rights to the users that protect them from arbitrary actions by the copyright holders.
In commercial software, the license terms are designed to protect the copyright. They're a way of granting a few rights to users while reserving as much legal territory is possible for the owner (the copyright holder). The copyright holder is very important, and the license logic so restrictive that the exact technicalities of the license terms are usually unimportant.
In free software, the situation is usually the exact opposite; the copyright exists to protect the license. The only rights the copyright holder always keeps are to enforce the license and to change the license terms of future versions. Otherwise, only a few rights are reserved and most choices pass to the user. In particular, the copyright holder cannot change the terms on a copy you already have. Therefore, in free software the copyright holder is almost irrelevant -- but the license terms are very important.
The Debian Free Software Guidelines are the result of a great deal of thought about what makes software «free». Its constraints on licensing require that:
This is as good a definition of «free software» as anyone has ever come up with. All of the standard licenses (MIT, BSD, Artistic, FRS, and GPL/LGPL) meet it (though some, like GPL, have other restrictions which you should understand before choosing it).
Note that licenses which allow noncommercial use only do not qualify as free-software licenses, even if they are decorated with «GPL» or some other standard license. They discriminate against particular occupations, persons, and groups. They make life too complicated for CD-ROM distributors and others trying to spread Linux commercially.
The MIT or X Consortium license has these terms. .
Most «shareware» licenses have terms like this as well. They may request a donation, but they don't make it a condition of use.
The BSD license is the best-known license of this kind. Among parts of the free-software cullture that trace their lineages back to BSD Unix, this license is used even on a lot of free software that was written thousands of miles from Berkeley.
It is also not uncommon to find minor variants of the BSD license that change the copyright holder and omit the advertising requirement (making it effectively equivalent to the MIT license). These licenses are called «BSD-like».
The `Artistic License', devised for Perl and widely used in the Perl developer community, is of this kind. It requires modified files to contain «prominent notice» that they have been altered. It also requires people who redistribute changes to make them freely available and make efforts to propagate them back to the free-software community.
FRS is a license class made up for use in Sunsite's LSM files. It stands for «Freely Redistributable Software». An FRS license grants unrestricted rights to copy, use, and locally modify. It must grant the right to redistribute modified binaries, and must fulfill the other terms of the Debian license guidelines.
You should use `FRS' in the Copying-Policy code if your license restricts redistribution of modified binaries more closely than the Artistic license, but fulfills the Debian guidelines.
The GPL also requires that interactive programs licensed under GPL include a startup banner referring to the GPL. It also requires that any program containing parts that are under GPL be wholly GPLed. (The exact circumstances that trigger this requirement are not perfectly clear to everybody.)
These extra requirements actually make the GPL more restrictive than any of the other commonly-used licenses. (Larry Wall developed the Artistic License to avoid them while serving many of the same objectives.)