Reverb (short for reverberation) happens when a sound continues after it has been produced. It is created when a sound is reflected many times so that a large number of reflections of the sound build up and then decay away as it is absorbed by the surfaces and objects in the space. This is different to an echo, which is a single reflection of a sound so that we can hear it repeated. We associate this effect with sounds made in large spaces, but it can also be created electronically. You can hear reverb in action when you go to the swimming pool!