This is defined here: https://github.com/kubernetes/community/blob/b3349d5b1354df814b67bbdee6890477f3c250cb/contributors/design-proposals/release/versioning.md#

This is defined here: https://github.com/kubernetes/community/blob/b3349d5b1354df814b67bbdee6890477f3c250cb/contributors/design-proposals/release/versioning.md#supported-releases-and-component-skew https://github.com/kubernetes/community/blob/b3349d5b1354df8... Specifically, a supported release is one which will receive patch updates (e.g. for security flaws or other issues). If you do not use a "supported version", you'll have to scramble to update or backport patches yourself if you're hit by a serious issue that is fixed upstream.