An overdrive guitar pedal is kind of like a less harsh distortion pedal. Technically speaking, whereas a distortion pedal clips an amplified waveform at a particular height, the overdrive pedal actually rounds the top of the clipped wave. While this still makes it a bit fuzzy when you crank up the gain, it sounds less extreme than a distortion or fuzz pedal. What is cool about this pedal is that it adds a little extra warmth to your signal when you are strumming gently, but when you really strum hard, the audio spikes up into crunchy distortion territory. While this is generally a very subtle effect, it is actually quite robust in terms of the different types of sounds that you can get out of it. It is great for adding a little something extra to any effects chain.