GNU (pronounced "g-new") is a free Unix-like operating system distributed by the Free Software Foundation. It is available in several different versions, but the most popular is the GNU/Linux system, which uses the Linux kernel. Since the GNU/Linux system is a popular version of Linux, it is often referred to as simply "Linux." However, GNU/Linux is technically a specific version of Linux developed by the GNU Project.
Several GNU/Linux distributions are available, including BLAG, Dragora, gNewSense, Kongoni, Musix GNU+Linux, Trisquel, Ututo, and Venenux. While each version of GNU/Linux is based on the GNU system, each has a custom user interface and may include unique bundled applications. For example, Trisquel is designed for small business and home and educational purposes, while Musix GNU+Linux is designed primarily for audio production.
GNU operating systems, software programs, and development tools, such as the GNU Compiler Collection (GCC), are distributed for free under the GNU General Public License (GPL). This license states that the software may be freely used, modified, and distributed. Therefore, all GNU software is freely available without a commercial license. Many freeware programs developed for other operating systems are now distributed under the GNU General Public License as well.
The name "GNU" is a recursive acronym for "GNU's Not Unix."