CentOS

Launched in late 2003, CentOS is a community project with the goals of rebuilding the source code for Red Hat Enterprise Linux (RHEL) into an installable Linux distribution and to provide timely security updates for all included software packages. To put in more bluntly, CentOS is nothing more than a clone of RHEL. The only technical difference between the two is branding - CentOS replaces all Red Hat trademarks and logos with its own. But the connection between RHEL and CentOS is not immediately visible on the CentOS web site; due to trademark laws, Red Hat is referred to as a "Prominent North American Enterprise Linux Vendor", instead of its proper name. Nevertheless, the relations between Red Hat and CentOS remain amicable and many CentOS developers are in active contact with Red Hat engineers.

CentOS is often seen as a reliable server distribution. It comes with the same set of well-tested and stable Linux kernel and software packages that form the basis of its parent, Red Hat Enterprise Linux. Despite being a community project run by volunteers, it has gained a reputation of being a solid, free alternative to the more costly server products on the market, especially among the experienced Linux system administrators. CentOS is also suitable as an enterprise desktop solution, specifically where stability, reliability and long-term support are preferred over latest software and features. Like RHEL, CentOS is supported with a minimum of 5 years of security updates.

Despite its advantages, CentOS might not be the best solution in all deployment scenarios. Those users who prefer a distribution with the latest Linux technologies and newest software packages should look elsewhere. Major CentOS versions, which follow RHEL versioning, are only released every 2 - 3 years, while "point" releases (e.g. 5.1) tend to arrive in 6 - 9 month intervals. The point releases do not usually contain any major features (although they do sometimes include support for more recent hardware) and only a handful of software packages may get updated to newer versions. The Linux kernel, the base system and most application versions remain unchanged, but occasionally a newer version of an important software package (e.g. OpenOffice.org or Firefox) may be provided on an experimental basis. As a side project, CentOS also builds updated packages for the users of its distributions, but the repositories containing them are not enabled by default as they may break upstream compatibility.

Pros: Extremely well-tested, stable and reliable; free to download and use; comes with 5-years of free security updates; prompt releases and security updates
Cons: Lacks latest Linux technologies; by the time of release, most software packages are outdated
Software package management: YUM graphical and command line utility using RPM packages
Available editions: Installation DVDs and installable live CDs (with GNOME) for i386 and x86_64 processors; older versions (3.x and 4.x) also available for Alpha, IA64 and IBM z-series (s390, s390x) processors.
Other RHEL clones and CentOS-based distributions: Scientific Linux, SME Server, StartCom Enterprise Linux, Fermi Linux, Rocks Cluster Distribution, Oracle Enterprise Linux