A Legal Issues Primer for Open Source and Free Software Projects: All software is subject to copyright law. The moment you save code to a file, copyright law gives you certain rights to control what other people can do with your work. Because almost everybody who contributes code to a software project has rights with respect to their code, understanding the basics of copyright is essential to running a FOSS project.
A software copyright is the exclusive legal right to control the rules for copying, modifying, and distributing a work of software. A person (or company, foundation, trust, or other legal entity) who has these exclusive legal rights is called a “copyright holder”. Legal rules prohibit non-copyright holders from copying, modifying or distributing copyrighted works without permission from the copyright holder.