Reverb – Is an effect that simulates the sensation of sound bouncing off the surfaces in a confined environment

To remember what reverb means use the following mnemonic:

Think of reverb as reversing and bouncing (reverb) around a room. 

Basic reverb looks like the following.

Reverb is an effect that simulates the natural acoustic environment of a space. It works by creating a dense collection of echoes that blend together, giving the impression that the sound is reverberating off of multiple surfaces. This effect is often used to add depth and warmth to a sound as well as creating the effect that the sound was recorded in a larger space. If you go into an empty hall and scream, you'll listen to your voice sustaining longer than usual, this is reverberation in action. 

See below for reverberation in action: