FreeBSD is a UNIX-like operating system for the i386, amd64, IA-64, arm, MIPS, powerpc, ppc64, PC-98 and UltraSPARC platforms based on U.C. Berkeley's "4.4BSD-Lite" release, with some "4.4BSD-Lite2" enhancements.
FreeBSD comes with over 20,000 packages (pre-compiled software that is bundled for easy installation), covering a wide range of areas: from server software, databases and web servers, to desktop software, games, web browsers and business software - all free and easy to install.
FreeBSD 8.3-RELEASE notes:
This is the fourth release from the 8-STABLE branch which improves on the functionality of FreeBSD 8.2 and introduces some new features.
Some of the highlights: usb(4) now supports the USB packet filter; TCP/IP stack now supports the mod_cc(9) pluggable congestion control framework; graid(8) GEOM class added to support various BIOS-based software RAID controllers (replacement for ataraid(4)); ZFS subsystem updated to SPA version 28; GNOME version 2.32.1, KDE version 4.7.4. FreeBSD 8.3-RELEASE is now available for the amd64, i386, pc98, and sparc64 architectures.