Feces (or faeces), also called poo, poop, shit, turd, stool, or number 2 is the body's solid waste left over from eating food. Human feces leave the intestinal tract and are removed from the body through the anus. Feces are known for their unpleasant odor. The color, which can range from dark green through brown (the most common color) to bright yellow, depends on a lot of different things; for example, different foods can change the color of feces, as can some illnesses, like diarrhea. The consistency of feces changes too. In humans it is measured using the Bristol stool scale, a system for separating feces into 7 different types. It is used for medical diagnosis.