Effects unit

An effects unit or pedal is an electronic device that alters how a musical instrument or other audio source sounds. Some effects subtly "color" a sound while others transform it dramatically. Musicians use effects units during live performances or in the studio, typically with electric guitar, electronic keyboard, electric piano or electric bass. While most frequently used with electric or electronic instruments, effects can also be used with acoustic instruments, drums and vocals. Examples of common effects units include wah-wah pedals, fuzzboxes and reverb units.