Did you type something you did not want to and want to quickly go back?
Made a couple edits you did not mean to?
Hopefully this will quickly get you back on track.
Ctrl + Z and Ctrl + Y
Pressing Ctrl + Z will undo any change. For example, if you cut text, pressing this key combination will undo the cut.
These shortcuts can also be pressed multiple times to undo or redo multiple changes. Pressing Ctrl + Y would redo the undo.
This does not always work with all programs, closed the page or already pressed save but it can be helpful in a lot of situations.