Q:

when we merge a branch in some other branch, then either local branches are merged or remote branch merged

If I merge branch a in b, after merging i have to push then branch for update the remote branch or merge updates remotes branch?

A:

You have to push. When you merge, you're only working with branches in your repo. If you want to publish them to your public (GitHub) repo, you have to push them out (just like any change).

