From Wikipedia

Red Hat Enterprise Linux (RHEL) is a Linux distribution developed by Red Hat and targeted toward the commercial market. Red Hat Enterprise Linux is released in server versions for x86, x86-64, Itanium, PowerPC and IBM System z, and desktop versions for x86 and x86-64. All of the Red Hat’s official support and training, together with the Red Hat Certification Program, focuses on the Red Hat Enterprise Linux platform. Red Hat Enterprise Linux is often abbreviated to RHEL, although this is not an official designation.[4]

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.

Red Hat uses strict trademark rules to restrict free re-distribution of their officially supported versions of Red Hat Enterprise Linux,[5] but still freely provides its source code. Third-party derivatives can be built and redistributed by stripping away non-free components like Red Hat’s trademarks, including community-supported distributions like CentOS and Scientific Linux, and commercial forks like Oracle Linux, which aim to offer 100% binary compatibility with Red Hat Enterprise Linux.

Version Release Date End of Production 1 Phase End of Production 2 Phase End of Production 3 Phase End of Extended Lifecycle Support
Red Hat Enterprise Linux 6 10 November 2010 Q2 2016 Q2 2017 30 November 2020 N/A
Current stable version: Red Hat Enterprise Linux 7 10 June 2014[32] Q4 2019 Q4 2020 30 June 2024 N/A

RHEL 6

Red Hat Enterprise Linux 6 was forked from Fedora 12 and contains many backported features from Fedora 13 and 14.

  • Red Hat Enterprise Linux 6 (Santiago), 10 November 2010 Uses Linux kernel 2.6.32-71[21]
    • 6.1, also termed Update 1, 19 May 2011 (kernel 2.6.32-131)[21]
    • 6.2, also termed Update 2, 6 December 2011 (kernel 2.6.32-220)[21]
    • 6.3, also termed Update 3, 20 June 2012 (kernel 2.6.32-279)[21]
    • 6.4, also termed Update 4, 21 February 2013 (kernel 2.6.32-358)[21]
    • 6.5, also termed Update 5, 21 November 2013 (kernel 2.6.32-431)[21]
    • 6.6, also termed Update 6, 13 October 2014 (kernel 2.6.32-504)[21]

RHEL 7

Red Hat Enterprise Linux 7 (Maipo) is based on Fedora 19, upstream Linux kernel 3.10, systemd 208, and GNOME 3.8.[23] The first beta was announced on 11 December 2013,[12][24] and a release candidate was made available on 15 April 2014.[25] On 10 June 2014 Red Hat Enterprise Linux 7 was officially released.[26]

  • Red Hat Enterprise Linux 7.0 (Maipo), 10 June 2014 Uses Linux kernel 3.10.0-123[21]
    • 7.1, also termed Update 1, available on 5 March 2015 (kernel 3.10.0-229)[21][27]