FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon),

amd64 compatible (including Opteron, Athlon64, and EM64T), ARM, IA-64, PC-98 and UltraSPARC 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.

http://www.freebsd.org/ja/