Delay is a very useful effect which repeats your signal back like an echo.

A digital delay allows you to play complementary parts with your own playing as one signal can repeat while you play another. The main variables are level which controls the volume of the delayed signal, time which sets the length of the delay and feedback or hold which controls the number of repeats for the delay. More elaborate delay units offer you different types of delay including decay rates and stereo options.

The following example is from "Inner Wilderness" by Arkenstone and it shows how delay can be used to build up the beginning of a song.