Software Licenses
A software license is a legal document that claims to modify the rights granted by copyright law.
- don’t typically sign this license, but may click a button
- aka End User License Agreement (EULA)
- open source software typically comes with a license in a file called COPYING
- license can modify copyright terms to make the terms either more or less restrictive
- generally, licenses for:
- proprietary software restrict your rights under copyright law
- open source software grants you additional rights
Background
Software is a type of intellectual property (IP) that is governed by copyright laws and patent laws.
A copyright is a legally recognized right to create a copy of something.
- typically forbids the copying of a work
- this does not translate well to software
- e.g.
- copy of a program from an installation medium to a disk drive
- copy of a program from the disk drive to random access memory (RAM)
- copy of RAM into swap space
- copy of RAM into various smaller caches on the motherboard or CPU to improve performance
- disk drive backups to protect against disk failures
- e.g.
Approaches to Software Licenses
Free Software
Free software licenses are those created to protect the four software freedoms as expressed by the Free Software Foundation (FSF).
- often referred to as copyleft
- not liked too much by businesses as it disrupts their ability to make money
Copyleft licenses ensure the four freedoms of FSF and require that any modified programs derived can be distributed only under the same license terms of the original program.
- aka reciprocal licensing
- inspired by FSF principles
- play on copyright
- created to ensure the opposite freedoms
- guarantee the freedom of users to copy software, rather than restrict the right
Licenses
Open Source
Open source licenses are those certified by the Open Source Initiative (OSI) as a softened version of free software more amenable to businesses.
- main difference:
- derived work is not required to be distributed under the same license
- certified many licenses as open source
- including GPL
- many licenses are called permissive licenses
Permissive licenses allow users to copy, share, and modify the software (like copyleft), but have minimal requirements for distribution, allowing additional or different licenses for the software (unlike copyleft).
- aka unreciprocal licensing
Open Source Licenses
Creative Commons
- objective is broader than just software
- licenses aimed at audio, video, textual works, etc.
- helps promote software freedom
- Creative Commons (CC)
- founded by Lawrence Lessig
- goal is to combat what its creators view as a creative culture that is increasingly tied to permissions granted (or not granted) by those who hold copyrights on earlier works
- 6 licenses designed for various purposes