Git Change Commit Command

use git check to change to different commits, checkout is a great command in git to change to different commits in your depository

git checkout commit_id

once you have send the command, you will get a notice: you are in 'detached HEAD' state. this means you are not working on the new commit that you changed to and not the HEEAD so how do you change back to the HEAD? UPDATE, i found the answer to go to back to the last master HEAD commt on this page: