Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium? and Athlon?), amd64 compatible (including Opteron?, Athlon 64, and EM64T), UltraSPARC?, IA-64, PC-98 and ARM architectures. It 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. Additional platforms are in various stages of development.
