CentOS stands for the Community Enterprise Operating System. It is a distribution of the Linux operating system based on Red HatEnterprise Linux (RHEL). It runs on the x86 PAE and x86-64 architectures and is currently the most popular Linux distribution for web servers.
CentOS uses the Red Hat source code base to create a product similar to RHEL. Unlike RHEL however, CentOS does not require a paid subscription. Its product support is conducted entirely through community mailing lists, web forums, and chat rooms. The developers are also supported through donations and organizational sponsorships.