What is Free Software?

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``Free software'' is a matter of liberty, not price. To understand the concept, you should think of ``free speech'', not ``free beer.''

``Free software'' refers to the users' freedom to run, copy, distribute, study, change and improve the software. More precisely, it refers to three levels of freedom:

The freedom to study how the program works and adapt it to your needs.
The freedom to redistribute copies so you can share with your neighbor.
The freedom to improve the program, and release your improvements to the public, so that the whole community benefits.

You may have paid money to get copies of GNU software, or you may have obtained copies at no charge. But regardless of how you got your copies, you always have the freedom to copy and change the software. In the GNU project, we use ``copyleft'' to protect these freedoms legally for everyone.

See Categories of Free Software (18k characters) for a description of how ``free software,'' ``copylefted software'' and other categories of software relate to each other.

When talking about free software, it is best to avoid using terms like ``give away'' or ``for free'', because those terms imply that the issue is about price, not freedom. Some common terms such as ``piracy'' embody opinions we hope you won't endorse. See Confusing Words and Phrases that are Worth Avoiding for a discussion of these terms.

What is Free Software?

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