Roughly one month after the release of Red Hat Enterprise Linux 5, the CentOS Project has caught up with its benchmark and released CentOS 5. The enterprise and server-class Linux distribution is now downloadable for 32 and 64-bit x86 (AMD-style x86_64) machines. Upcoming releases of CentOS will add builds for Sun SPARC, IA-64 (Intel Itanium), and PowerPC machines. CentOS offers a semi-automated upgrade path from the previous release, but upgrades directly from CentOS 3 are not recommended.
Although Oracle has made news lately with its own Red Hat-derived Linux, CentOS is still generally regarded as the most prominent and widely-used Red Hat clone. CentOS and its peers recompile the source code to Red Hat Enterprise Linux (published under the terms of the GPL and other open-source licenses which govern the vast majority of any Linux distribution) while trying to judiciously avoid any trademark infringement or other violations of Red Hat proprietary marks or technology. The end result is an operating system which operates very much like the "upstream" product but without the attached software and support costs generally imposed by Red Hat.
Exact numbers on CentOS are difficult to come by, but it is a well-regarded platform in the public Web hosting space. The CentOS Project maintains its own security and support personnel, albeit on a different level than the larger, publicly-held Red Hat.
