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.
Planet FreeBSD is a collection of links and blogs from the developers. I find this a great thing, it is nice to be informed, what other people currently work on and just what happens inside the project.