Distortion

One of more commonly known effects for musicians is distortion. It falls into the family of effects sometimes referred to as "dirt" boxes: Distortion, Overdrive, and Fuzz. In simple terms, it is cutting the top and bottom of the sound wave off using a technique known as "hard" clipping to create a more square shaped wave instead of the more natural sine wave formation. A solid explanation on the techniques and methods of creating different types of distortion can be found on Wikipedia.