git merge & rebase: Do they only affect the currently checked out branch?

Question

Is it correct to say that the following two commands

git merge X
git rebase X

only change/affect the current branch and not X (or any other branch)?

I think I understand what both commands do, but I want to make sure my assumption is correct.

Answer 1

Yes, your assumption is correct. Both commands will affect only the branch you're on when you run the command.