Software license

A software license is a legal instrument (usually by way of contract law, with or without printed material) governing the use or redistribution of software. Under United States copyright law all software is copyright protected, in source code as also object code form. The only exception is software in the public domain. A typical software license grants the licensee, typically an end-user, permission to use one or more copies of software in ways where such a use would otherwise potentially constitute copyright infringement of the software owner's exclusive rights under copyright law.

Software licenses and copyright law

Most distributed software can be categorized according their license types (see table).

Two common categories for software under copyright law, and therefore with licenses which grant the licensee specific rights, are proprietary software and free and open source software (FOSS). The distinct conceptual difference between both is the granting of rights to modify and re-use a software product obtained by a customer: FOSS software licenses the customer both rights and bundle therefore the modifiable source code with the software ("open-source"), proprietary software doesn't licenses typically these rights and keep the source code therefore hidden ("closed source").