As legendary guitar player Tom Morello once said, a whammy pedal is essential for making those awesome pterodactyl sounds. but what even is a guitar effects pedal? simply, it changes the sound a guitar makes somewhere between playing the strings and the sound coming out of the amp. For now, we'll just focus on distortion pedals which are probably the most common pedals. Distortion pedals will distort the "clean sound" a guitar makes before the effect of the pedal is added in. When a guitar is played, sound is picked up by the pickups and sent through the quarter inch jack in the form of an electronic signal that corresponds to a sound wave. When this wave reaches the distortion pedal, depending on the circuit within the given distortion pedal, it will change the shape of the sound wave generally change the shape of the peaks and troughs of the wave, and then send the through to the amplifier, resulting in a distorted sound as the final product. Distortion pedals will generally have a knob that lets the user control how intense the effect is, or how much you will distort the wave.