A
Unix commonly used for huge
server farms in the
real world. FreeBSD represents an
idealized form of
software development characterized by multiple
branches with
varying degrees of
stability (
-CURRENT,
-STABLE).
FreeBSD usually runs on x86 computers, but has a quite successful Alpha port and will be ported to IA-64 and more, although it probably won't be ported to as many platforms as NetBSD. One nice feature of FreeBSD is that the committers have the ability to merge code from BSD/OS (such as a coming PowerPC port), resulting in more potential platforms and many more developers.
FreeBSD is often characterized by its coherence and generally well-thought-out structure and implementation, as well as very nice mailing lists. Notable recent inclusions have been kqueue, encryption in the base system, IPv6 support from KAME, and the start of SMPng.