Undo

Undo is a command in many computer programs. It erases the last change done to the document reverting it to an older state. In some more advanced programs such as graphic processing, undo will negate the last command done to the file being edited.

The opposite of undo is redo. The redo command reverses the undo or advances the buffer to a more current state.

In most Windows applications, the Undo command is activated by pressing the Ctrl+Z or Alt+Backspace keybindings. In virtually all Macintosh applications, the Undo command is activated by pressing Command-Z. The common command for Redo on Microsoft Windows systems is Ctrl+Y or Ctrl+Shift+Z. The common command for Redo on Apple Macintosh systems is Command-Shift-Z.