How are 'Active' branches determined?

In the branches page, there is a tab for ‘Active’ branches. How is a branch determined to be active? I looked up the help doc but I couldn’t find any info about active branches there: Branches | GitLab

Hi @bat-signal

This is a bit of a guess, but I think it’s the time between “now” and the last push to the branch. Certainly, all my stale branches are the older ones.