Red Hat Enterprise Linux is a Linux distribution produced by Red Hat and targeted toward the commercial market, including mainframes. Red Hat commits to supporting each version of Red Hat Enterprise Linux for 7 years after its release. All of Red Hat's official support, all of Red Hat's training and the Red Hat Certification Program center on the Red Hat Enterprise Linux platform. Red Hat Enterprise Linux is often abbreviated to RHEL, but Red Hat is now attempting to discourage this.

New versions of Red Hat Enterprise Linux are released every 18 to 24 months. When Red Hat releases a new version of Red Hat Enterprise Linux, customers may upgrade to the new version at no additional charge as long as they are in possession of a current subscription (i.e. the subscription term has not yet lapsed).

Red Hat's first Enterprise offering (Red Hat Linux 6.2E) essentially consisted of a version of Red Hat Linux 6.2 with different support levels, and without separate engineering.

The first version of Red Hat Enterprise Linux to bear the name originally came onto the market as "Red Hat Linux Advanced Server". In 2003 Red Hat rebranded Red Hat Linux Advanced Server to "Red Hat Enterprise Linux AS", and added two more variants, Red Hat Enterprise Linux ES and Red Hat Enterprise Linux WS.

Verbatim copying and redistribution of the entire Red Hat Enterprise Linux distribution is not permitted due to trademark restrictions. However, there are several redistributions of Red Hat Enterprise Linux minus trademarked features (such as logos and the name).

Variants

As of 2005 Red Hat distributed four variants of Red Hat Enterprise Linux:

• Red Hat Enterprise Linux AS for mission-critical/enterprise computer systems.
• Red Hat Enterprise Linux ES for supported network servers
• Red Hat Enterprise Linux WS for technical power-user desktops or high-performance computing
• Red Hat Desktop – for multiple deployments of single-user desktops

There are also "Academic" editions of the Desktop and Server variants. They are offered to schools and students, are less expensive, and are provided with Red Hat technical support as an optional extra. Web support based on number of customer contacts can be purchased separately.

It is often assumed the branding ES and AS stand for "Enterprise Server" and "Advanced Server", respectively. The reason for this is that the ES product is indeed the company's base enterprise server product, while AS is the more advanced product. However, nowhere on its site or in its literature does Red Hat say what AS, ES and WS stand for. In contrast, Novell has a competing server distribution called SUSE Linux Enterprise Server, which is abbreviated to SLES.

In Red Hat Enterprise Linux 5 there are new editions that substitute former Red Hat Enterprise Linux AS/ES/WS/Desktop:

• Red Hat Enterprise Linux Advanced Platform (former AS)
• Red Hat Enterprise Linux (former ES) (limited up to 2 CPUs)
• Red Hat Enterprise Linux Desktop with Workstation and Multi-OS option
• Red Hat Enterprise Linux Desktop with Workstation option (former WS)
• Red Hat Enterprise Linux Desktop with Multi-OS option
• Red Hat Enterprise Linux Desktop (former Desktop)