Linux is available under the <link xlink:href="http://www.fsf.org/copyleft/gpl.html">GNU General Public License</link> (GPL), which is designed to eliminate closed source software. In particular, any derivative work of a product released under the GPL must also be supplied with source code if requested. By contrast, the <link xlink:href="http://www.opensource.org/licenses/bsd-license.html">BSD license</link> is less restrictive: binary-only distributions are allowed. This is particularly attractive for embedded applications.