There are many different kinds of delay but it is typically an echo of whatever is being played. The speed of the delay can be adjusted and there are even tap delays available so that you can set it to the same tempo of your drummer or backing track. Other factors that can usually be adjusted are the feedback (how long the delay lasts) and Dry/Wet (how much delay is in the mix). Some different types of delay include Digital Delay, Stereo Delay, and Ping Pong Delay. A ping pong delay is when the signal bounces across the stereo field.