The Mozilla Public License (MPL) is a free, open source, and detailed software license developed and maintained by the Mozilla Foundation. It is characterized as a hybridization of the modified BSD license and GNU General Public License (GPL) that seeks to balance the concerns of proprietary and open source developers.
The MPL is the license for the Mozilla Firefox, Mozilla Thunderbird, and most other Mozilla software, but it has been used by others, such as Adobe to license their Flex product line, and LibreOffice 4.0 (also on GPL 3+). Version 1.1 was also notably adapted by companies to form derivative licenses like Sun Microsystems' own Common Development and Distribution License.
Borrowed from Wikipedia on MPL