"After tremolo, fuzz and reverb, wah-wah is one of the earliest effects, and certainly one of the most expressive. Its interactive nature means everyone uses the wah-wah a little differently. Some players rock the pedal in time with the song. Others use it to outline phrases. Others use it as a tone filter. That sense of individuality is a great metaphor for the guitar itself; all distilled down into a space small enough to fit under your foot. Here are the 10 best wah-wah solos."