In computing, undo (short for undoing) is the ability to reverse the effects of one or more actions. The undo command is usually available in the edit menu of a software application.

Undoing a single action is often quite simple. For example, in a word processor, the user might select the “undo” command from the Edit menu after typing a word by mistake. This would reverse the last typed character.

However, undoing multiple actions can be more complicated, especially if the application stores undo information in a history buffer. In this case, the “undo” command might not only reverse the …