CentOS (/ˈsɛntɒs/, from Community Enterprise Operating System) is a Linux distribution that provides a free, enterprise-class, community-supported computing platform functionally compatible with its upstream source, Red Hat Enterprise Linux (RHEL). In January 2014, CentOS announced the official joining with Red Hat while staying independent from RHEL, under a new CentOS governing board.
The first CentOS release in May 2004, numbered as CentOS version 2, was forked from RHEL version 2.1AS. Since the release of version 7.0, CentOS officially supports only the x86-64 architecture, while versions older than 7.0-1406 also support IA-32 with Physical Address Extension (PAE). As of December 2015, AltArch releases of CentOS 7 are available for the IA-32 architecture, Power architecture, and for the ARMv7hl and AArch64 variants of the ARM architecture.