From Academic Kids
Feces (American spelling) or faeces/fæces (British spelling) are semi-solid waste products from an animal digestive tract expelled through the anus (or cloaca) during defecation. In humans, defecation may occur (depending on the individual and the circumstances) from once every two or three days to many times a day. Prolonged interruption in the usual routine is called constipation.
The distinctive odor of feces is due to bacterial action. Bacteria produce compounds such as indole, skatole, and mercaptans, which are rich in sulfur, as well as the inorganic gas hydrogen sulfide. These are the same compounds that are responsible for the odor of flatus.
Feces can help scientists learn about animals because of the food an animal eats.
Feces are generally a taboo subject (see toilet humour). Scientists have long noted that many species hide or bury their feces, because the odor can attract predators, and these species often exhibit anxious behavior when their feces cannot be concealed. In humans, this phenomenon manifests itself in a stigma on feces.