When it comes to major releases of operating systems, it’s important to be aware of how recent each release is. Many vendors support current and previous releases for all the OS updates, but as releases get older they get fewer updates due to challenges with backporting – which means majority of such updates are security related.
OS release version is also important because it will indicate how much of commercial support your environment still has. It is critical that production systems stay supported by your OS vendor and older release are phased out well before they reach end-of-life (EOL).
End-Of-Life (EOL) is the date assigned to each major OS and software release that indicates when your product will not only stop receiving software updates but will also stop being commercially supported by your vendor.
Red Hat Enterprise Linux Life Cycle
RHEL6 and RHEL7 OS releases receive 10 years of support: 5 years of full support plus 5 more years of the maintenance support.
Full support means your operating system is actively developed and each minor release upgrade brings hundreds of bug fixes and package updates. You also get new functionality as it’s developed and introduced by the vendor.
Maintenance support indicates that you should start looking at upgrading to the next major release (like RHEL8), because your current release is no longer actively developed – but still maintained with bug and security fixes.