FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called "UNIX", as the direct descendant of BSD UNIX (many of whose original developers became FreeBSD developers), FreeBSD's internals and system APIs are UNIX-compliant. Thanks to its permissive licensing terms, much of FreeBSD’s code base has become an integral part of other operating systems such as OS X that have subsequently been certified as UNIX-compliant and have formally received UNIX branding. With the exception of the proprietary OS X, FreeBSD is the most widely used BSD-derived operating system in terms of number of installed computers, and is the most widely used freely licensed, open-source BSD distribution, accounting for more than three-quarters of all installed systems running free, open-source BSD derivatives.

FreeBSD ist ein freies, unixartiges Betriebssystem aus der BSD-Familie.

FreeBSD är ett fritt BSD-baserat operativsystem med inriktning på stabilitet och prestanda.

FreeBSD – popularny system operacyjny z rodziny Unix. Do wersji 2.0 wywodził się z systemu 4.3BSD, kolejne wersje wywodziły się z 4.4BSD Lite2; obu stworzonych przez Computer Systems Research Group (CSRG) na Uniwersytecie Kalifornijskim w Berkeley. Podobnie jak NetBSD, jest bezpośrednią pochodną 386BSD - systemu będącego pierwszą próbą przeportowania systemu Unix z gałęzi BSD na architekturę IA-32. Początkowo znany pod nazwą Unofficial 386BSD Patchkit.

FreeBSD è un sistema operativo libero di tipo UNIX, derivato dalla Distribuzione Unix dell'Universita' Berkeley, e disponibile per piattaforma Intel IA-32, AMD64, DEC Alpha, IA-64, PC-98, UltraSPARC, PowerPC ed altre.