Debian is a free operating system for your computer. Debian uses the Linux kernel (the core of an operating system), but most of the basic OS tools come from the GNU project; hence the name GNU/Linux
Since 1983, developing the free UNIX style operating system GNU, so that computer users can have the freedom to share and improve the software they use.
The top free UNIX and Linux System Administration Resource Forum, for beginners and gurus that are looking for UNIX and Linux help and advice on the Internet
The Linux Documentation Project is working towards developing free, high quality documentation for the Linux operating system. The overall goal of the LDP is to collaborate in all of the issues of Linux documentation.
FreeBSD® operating system is derived from BSD, the version of UNIX® developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals.