CentOS is a freely available Linux distribution which is based on Red Hat's commercial Red Hat Enterprise Linux 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.
Red Hat Enterprise Linux is largely composed of free and open source software, but is made available in a usable, binary form (such as on CD-ROM or DVD-ROM) only to paid subscribers. As required, Red Hat releases all source code for the product publicly under the terms of the GNU General Public License and other licenses. CentOS developers use that source code to create a final product which is very similar to Red Hat Enterprise Linux and freely available for download and use by the public, but not maintained or supported by Red Hat. There are other distributions derived from Red Hat Enterprise Linux's source as well, but they have not attained the surrounding community which CentOS has built; CentOS is generally the one most current with Red Hat's changes.
CentOS preferred software updating tool is based on yum, although support for use of an up2date variant exists. Each may be used to download and install both additional packages and their dependencies, and also to obtain and apply periodic and special (security) updates from repositories on the CentOS Mirror Network.
CentOS is perfectly usable for a X Window based desktop, but is perhaps more commonly used as a Server Operating system for Linux Web Hosting Servers. Many big name hosting companies rely on CentOS working together with the cPanel Control Panel to bring the performance and stability needed for their web-based applications.