For many years, some people believed it was impossible for a free and open source operating system like Red Hat Linux to be profitable. With the formulation of Red Hat Enterprise Linux, the company Red Hat proved that theory wrong and also established Linux as one of the most widely-used Unix server alternatives. It now threatens to supplant Unix completely and poses a serious threat to Microsoft’s Windows Server.
Red Hat Enterprise Linux is designed with servers in mind and therefore comes with many server requirements out of the box. Because it is a commercial Linux distribution, it has a wide range of certified hardware support and is licensed for every server that runs it. There are numerous versions of RHEL, including entry-level server, advanced server, and enterprise server editions.
Because RHEL is open source, there are also several free of charge community builds of the operating system. The only official Red Hat sponsored community version is called Fedora, which is actually ahead of RHEL in terms of package maturity. Others, such as CentOS, OracleLinux, and White Box Enterprise Linux maintain package compatibility with RHEL.
Red Hat uses the YUM package manager system to install, update, and remove applications. The project currently operates on a release cycle of approximately six months (for major updates) and can continue to support major releases for up to 13 years (on the extended life cycle).