Redo verses Undo

cowboyofhell is right, this is the best explanation of the difference between redo and undo. From the prefix "un" and "re". Both have different name and functionality. If you are working on something then you made a mistake and you want to change your mistake by writing again, then use undo. It will remove the mistake and you can rewrite again. If you use redo, it will redirect you back to your previous work before you made a mistake. Undo: Prev - Dog bark Present - Dog barks Undo - Dog bark - If you made a mistake by putting 's', when you press undo it will remove 's' from the present meaning, to undo or remove 's'. Redo: Prev - Dog bark Present - Dog barks Redo - Dog bark - If you made a mistake by putting 's'. when you press redo, it will redirect you to the previous work you create which is "Dog bark". Both have same output when you use but different in terms of behavior.