^ Control+Z is a control character in ASCII code. It is commonly used as a substitute (SUB) character. It is perhaps best known as the keyboard shortcut in Windows applications for the undo command. It is also used to signal an end-of-file on some operating systems.Strictly speaking, ^ Control+Z is not a printable character but a code for control purposes, though it is sometimes rendered by two characters as ^Z. It is generated by pressing the Z key while holding down the ^ Ctrl key on a computer keyboard.In many GUIs and applications ^ Control+Z can be used to undo the last action.