Feces (or faeces), also called poo, poop, 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.
Although feces are generally considered waste, they actually have many uses. Feces are used by some scientists to follow tiger populations. Feces from animals and humans can be used to create fertilizers for plant crops. Some feces are also used as a fuel for fires.
In informal language, there are many words for feces. These are often offensive or even vulgar. Examples include "shit", "poop", and "crap". Nonetheless, feces are a natural part of life's give and take.