- Fuzz pedals were among the first distortion pedals created. Earlier, a distortion effect was achieved by overdriving the amplifier itself. Unlike other types of distortion, which distort the signal by increasing gain beyond normal levels, a fuzz pedal distorts the signal by introducing a square wave into the signal output. The square wave breaks up the signal, producing the characteristic fuzz sound associated with classic rock artists such as Jimi Hendrix.
- High-gain pedals, the most basic type, increase the signal's gain until the amplifier's ability to process the signal accurately is overwhelmed to produce the harsh tones usually associated with heavy rock and metal music. They are distinguished from overdrive pedals mainly by the degree to which gain is increased. The tones they produce can resemble those of a fuzz pedal, but a high-gain pedal does not introduce new sound information into the signal.
- Valve-distortion pedals are high-gain or overdrive pedals with an integrated vacuum tube like those found in amplifiers. These pedals are specifically designed to reproduce the sound of an overdriven tube amplifier as closely as possible, even when using a solid-state amp. They generally produce a "rounded" distortion by preserving more harmonic information than solid-state pedals. Valve-distortion pedals are found in many kinds of music, but are particularly favored by blues and rock soloists.