Why ROS Lunar reached EOL before Kinetic

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why did the ros lunar reached EOL before its earlier version ros kinetic.

Because ROS Lunar was a regular release, while ROS Kinetic is a long term support release (LTS).

Regular releases receive(d) 2 year of support. LTS releases 5 year.

As Kinetic was released in 2016, and Lunar in 2017, this leads to Kinetic becoming EOL in 2021 and Lunar in 2019.

Compare this to Ubuntu's release cycle (which heavily influenced the one used for ROS) where they are called "Long term support and interim releases".

What is the criteria that decides a distributions EOL. ??

This is probably best explained by reading wiki/Distributions/ReleasePolicy.

As an answer here: the exact criteria are those we (including you, so the community) came up with when all of this was discussed. See again the wiki/Distributions/ReleasePolicy page which links to a number of different discussions on ROS Discourse and the ros-users mailing list.

For ROS 1, the only remaining release (Noetic) will be an LTS (see wiki/Distributions). For ROS 2, a similar page is located at index.ros.org/doc/ros2/Releases.