Poop (also called feces or excrement) is the solid waste that's left after we've digested our food. It's the stuff our bodies can't use for energy or growth, and it passes out of us when we go to the toilet. So poop is really just the final product of our digestive system. In this gut-wrenching guide we will explore how we digest our food, and all the strange side effects of this complex and fascinating process-including burps and farts. We will look at what happens when things go wrong, and how this affects the color, smell, and texture of our poop. We will also find out how poop is not just a smelly waste product, but can actually be useful to us.