CentOS (ˈsɛntɒs, from Community Enterprise Operating System; also known as CentOS Linux) is a discontinued Linux distribution that provided a free and open-source 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 version 8, CentOS officially supports the x86-64, ARM64, and POWER8 architectures, and releases up to version 6 also supported the IA-32 architecture. , AltArch releases of CentOS 7 are available for the IA-32 architecture, Power ISA, and for the ARMv7hl and AArch64 variants of the ARM architecture. CentOS 8 was released on 24 September 2019.
In December 2020, Red Hat unilaterally terminated CentOS development. In response, CentOS founder Gregory Kurtzer created the Rocky Linux project as a successor to the original mission of CentOS. In March 2021, Cloud Linux (makers of CloudLinux OS) released a new RHEL derivative called AlmaLinux.
CentOS Linux was discontinued at the end of 2021 in favor of CentOS Stream, a distribution positioned upstream of RHEL.
CentOS originated as a build of CAOS Linux, an RPM-based Linux distribution started by Gregory Kurtzer in 2002. Infiscale described its GravityOS as "[including] the small footprint of Caos", indicating a certain level of influence from the discontinued distribution.
In June 2006, David Parsley, the primary developer of Tao Linux (another RHEL clone), announced the retirement of Tao Linux and its rolling into CentOS development. Tao users migrated to the CentOS release via .
In July 2009, it was reported in an open letter on the CentOS Project web site that CentOS's founder, Lance Davis, had disappeared in 2008. Davis had ceased contribution to the project, but continued to hold the registration for the CentOS domain and PayPal account.