What are the major types of open source software licenses?
OSS licenses can be grouped into three main categories: Permissive, strongly protective, and weakly protective. Here is an explanation of these categories, along with common licenses used in each category (see The Free-Libre / Open Source Software (FLOSS) License Slide): • Permissive: These licenses permit the software to become proprietary (i.e., not OSS). This includes the MIT license and the revised BSD license. The Apache 2.0 license is also a popular license in this category; note that the Apache 2.0 license is compatible with GPL version 3, but not with GPL version 2. • Strongly Protective (aka strong copyleft): These licenses prevent the software from becoming proprietary, and instead enforce a “share and share alike” approach. In such licenses, if you give someone a binary of the program, you are obligated to give them the source code (perhaps upon request) under the same terms. This includes the most popular FLOSS license, the GNU General Public License (GPL). There are two ve