Guitar Effects (gətɑ́r əfɛ́kts) are devices used to enable a guitar player to alter the sound coming from the instrument. The traditional method of use is when a guitar is plugged into a guitar effect/s, which is then plugged into an amplification source. Guitar effects receive a signal from the guitar and then alter the signal before it is sent onto an amplifier.

There are a variety of guitar effects that are available. Effect levels can be increased or decreased and are most often controlled with foot pedals. Effects are used in combination to form recognizable tones and these combos enable the creation of signature sounds. Some of the more common effects include distortion and fuzz boxes, which exaggerate the vibratory levels of the strings resulting in a distorted sounds. Other effects include Flanger which adds a sweeping and revolving loop to the sound and Chorus which brightens the tone and multiplies the sound itself.