Sometimes you need enterprise-level software but cannot afford the enterprise-level price. Such is often the case with dedicated servers. Many individuals and companies operate on a limited budget and cannot afford to pay for licensing and support for an enterprise server OS such as Red Hat Enterprise Linux. Others simply may not need the paid support if they have a competent tech team on staff.
CentOS offers a nice alternative to Red Hat Enterprise Linux and other commercial distributions while still providing enterprise-grade security and stability. This is largely due to the fact that CentOS is based on the free and open source code of RHEL and maintains 100% binary compatibility with its upstream source. At one time CentOS was the most widely-used Linux distribution on web servers, but it has since been surpassed by Debian.
Essentially, using CentOS is like using RHEL without the brand recognition, support, or guarantees that come with the latter. Still, many server system administrators consider it reliable and easy to use. Like RHEL, it relies on RPM for packages and uses YUM for its package management updates and new installations.
CentOS is available for free download from the project’s website.