How undoing and redoing make editing easy.
Undoing your last action in Photoshop — or your last 10 or 20 actions — is as simple as tapping a few keys. Learn the ins and outs of time traveling through your work with the Undo and Redo actions.
How to save a snapshot of a specific history state.
If you want to save the current state so you can revert to it later in your work session, you can create a snapshot that Photoshop will save until the next time you close the document.