GPL
From Hackers-IL
GPL = (GNU) General Public License. The most commonly used license for free software, with more software than all the software with the other licenses combined. It is a copyleft license, which means every derivative work must be licensed under the same license. It also restricts the licenses that are allowed to link to it to a subset of the free software licenses out there. Note that as is the case with all free software, (but not necessarily every open-source one), making modifications for private or in-house used is allowed, as long as these modifications are not distributed outside the organization.
The GPL is very controversial, and contains many caveats. Its defendants will say that it is still considerably better than the EULAs of most commercial closed-source software.
A comparison of the GPL with the Perl Programming Language is in order. The more you are around the open-source world, the more you learn new things about the GPL, just like every Perl enthusiast will constantly learn new things about Perl.
