This page is obsolete. You should take a look at choosealicense.com instead; it’s much better.
Apache
- not copyleft
- about 3 pages long
CC0
- public domain
- plus a fallback license for jurisdictions that don’t have public domain
- this is the recommended way to dedicate a work to the public domain
GNU GPL
- the most popular FOSS license
- copyleft
- does not allow linking from code with other licenses
- about 10 pages long
GNU LGPL
- copyleft
- allows linking from code with other licenses
- defined as the GPL plus a page of additional terms
ISC
- only requires that the copyright info remain intact
- most readable license I have seen
- a single concise sentence
MIT
- only requires that the copyright info remain intact
- very readable
- a single wordy sentence
MPL
- weak copyleft, i.e. files containing MPL code can’t be relicensed under a different license, but can be used along side files containing code with other licenses in a “larger work”
- about 6 pages long
zlib
- requires that the copyright info remain intact
- modified versions must be labeled as such and cannot misrepresent the author of the original