Software license
- Definition
- A document that describes the obligations of users of the software

Without a license a software product is bound by copyright law. Only the maker of the software gets to decide who can copy it. The license is added by the maker to make their wishes with respect to copying, modification, and selling explict. Many standard licenses are available.
Examples
- MIT license
- GPL
- Commercial
When should you use it?
- If you want your software to be shared and you want to explain to potential users what you do and don't allow
How does it work?
Defines the terms under which software or content may be used, redistributed, or modified; a legal contract between provider and user.