The GPL or GNU Public License is a popular license for free and open source software. It is the license used by a number of Wincent products such as the Walrus, Wincent Build Tools, Wincent Strings Utility and WOTest.
It is considered by many to be "more free" than the BSD license but this is not strictly true. It is actually more restrictive, but in the sense that it imposes restrictions in order to guarantee the continuance of freedom. The BSD license, in comparison, is even more free, but that includes the freedom to deny others the same freedom. That is, the GPL ensures that once code is released under the GPL it will always remain free, but the BSD allows people to take free software and subsume it in closed source commercial offerings.