What is human feces made up of?

It is mostly eliminated waste that is deprived of most nutrients and energy (e.g., protein, fat, vitamins and carbohydrates) that your body has absorbed and used during the digestive process. It is made up of digested and also undigested food with 67% solid material. The other 33-34% is comprised of liquids that have not been absorbed. Some of the solids are also unused fats, undigested food particles, roughage, and fiber.

It has an odor because of the breakdown of the contents (by the natural "good" bacteria in your digestive system which are also present in the feces) which creates organic compounds rich in nitrogen and sulfur and gasses such as hydrogen sulfide, all of which are odorous.

It is usually colored brown because of the bilirubin it contains which is a yellow liquid produced by the body and used in digestion of fats which, when mixed with the iron from foods, other waste materials and the broken down food particles, creates the mostly brown color.

It comes out of your digestive tract after the useful parts have been extracted and it has been moved completely through the bowels with peristaltic action to the rectal area where it can then be evacuated from the anus.

Other terms for feces are poop, excrement, turds, caca, stool, BM, or poo but most of these are crude and some are even considered vulgar.

There can also be "bad" bacteria in feces which is why you are always told to wash your hands after using the restroom.