"Open Source", "Free Software" and other beasts

This document is copyrighted by Shlomi Fish under the Creative Commons Attribution License version 2.5 (or at your option a greater version).


The purpose of this document is to introduce the Open Source Software and Free Software world to people who are not familiar with it. It covers the semantics of the terms, the history of this world, philosophical differences, various criteria of open source software, and other issues.

Table of Contents

Software Licences and "Proprietary" Software
Meaning of the terms
Early Days, AT&T UNIX, BSD
Richard Stallman, the GNU Project, and the "Free Software" term
The Linux Kernel, GNU/Linux and the Debian Free Software Guidelines
The "Cathedral and the Bazaar" and the coining of the term "Open-Source"
Linux Becomes More Popular
Open Source and Open Content Become Mainstream
Difference between "Open Source" and "Free Software".
In for Free Beer
Other Criteria of Open Source Software
GPL Compatibility
Open Source vs. Sourceware
Myths about Open Source and Other Issues
Sharing software huh? Isn't it a bit like Communism?
The "Programmers Will be out of Work" because of Free Software Myth
Other Myths about Linux and Open Source Software
Where I Stand
Links and References
Resources for Further Reading
The GNU Project Philosophy
Eric S. Raymond's Writings
Joel on Software
David A. Wheeler's Site
Related Books
Document Information
To Do List


Many people will hear about Linux in the news, being the cool new operating system that everyone can use free of charge. Those who become interested in it enough or actually start working with it, will learn that it is made out of many independent "open source" components. Now, after enough time (perhaps very soon), they will learn that the term "free software" (where free is free as in "free speech" and not free as in "free beer") can be used as an alternative to the adjective "open source". But what is open source and free software? What distinguishes them from other software that is available to the public at no cost or is distributed as shareware?

Note that the terms "free software" and "open source" would be used throughout this article to refer to the same phenomenon. I do not religiously stick to either term.