In March of 2007, Red Hat first announced its Red Hat Enterprise Linux 5 ( RHEL) platform. Though it might seem quant today, RHEL 5 was particularly notable in that it was the first major release for Red Hat to emphasize virtualization, which is a feature all modern distros now take for granted.
Originally the plan was for RHEL 5 to have seven years of life, but that plan changed in 2012 when when Red Hat extended its standard support for RHEL 5 to 10 years.
This past week, Red Hat released RHEL 5.11 which is the final minor milestone release for RHEL 5.X. RHEL now enters what Red Hat calls it production 3 support which will last for another three years. During the production three phase no new functionality is added to the platform and Red Hat will only provide critical impact security fixes and urgent priority bug fixes.
Read more at Linux Planet.