CentOS the free RedHat, Version 5.0 released
By Rayed
CentOS is a freely available Linux distribution which is based on Red Hat’s commercial Red Hat Enterprise Linux (RHEL) product. This rebuild project strives to be 100% binary compatible with the upstream product, and within its mainline and updates, to not vary from that goal. Additional software archives hold later versions of such packages, along with other Free and Open Source Software RPM based packagings. CentOS stands for Community ENTerprise Operating System.
http://en.wikipedia.org/wiki/Centos