How to update a Git branch from another branch

Given a Git branch that's not up to date with another branch, how do you merge the changes?

I was working on a Git branch that was not up to date with changes I was doing on another branch.

So, I had to incorporate those changes. Given a Git branch that’s not up to date with another branch, how do you merge the changes?

You checkout the branch you want to update:

git checkout my-branch

and you merge from the branch you want to update from:

git merge another-branch