Delay is an effect in which the input signal is recorded to a storage medium then played back some time later. The amount of time it takes for the signal to be played back is typically variable and often times the signal is fed back into the signal path so that you keep getting fading repeats that simulate an echo. The early means of storage and playback were tape machines playing tape loops of various lengths with controls for adjusting the record and playback heads so that the delay time could be manipulated to fit the tune. The first delay machines were commercially available in the fifties.... Click on the title for more