Abuout life cycle of old branch

[abush wang]

Hi,
I have noticed that there are many old branch, like that
git branch -a
...
  remotes/origin/release/2.23/master
  remotes/origin/release/2.24/master
  remotes/origin/release/2.25/master
...

I was wandering that is there life cycle for old branch, such as they will
be maintained for many years.

Thanks