RedHat

RHEL (short for RedHat Enterprise Linux), is a commercial Linux distribution that was first released to the public in 2000. RHEL was primarily designed to accommodate enterprise class server applications and network environments.

RHEL OS releases and updates are distributed via a paid subscription service. Desktop and Server variants exist, and several tiers are available, including lower-cost Academic distributions for schools and students. In addition, its source code is freely available, and developers can request subscriptions, free of cost, provided they register with the Red Hat Developer Program and agree to RHEL licensing terms.