Table 1.

The mainstream open-source licenses can be categorized based on the permissiveness required by license terms.

Category	Licenses*	Permissiveness
Public Domain	Unlicense, CC, WTFPL	No legal restrictions
Permisive	MIT, ISC, Apache, BSD, BSL, Artistic, Zlib, AFL	Include a copy of the license and attribution to the authors.
Weak Copyleft	MPL, EPL, LGPL	Release part of code under the same license
Strong Copyleft	GPL, AGPL	Release the entire program under the same license

^*Some may represent a series of licenses with different versions.