A bowel movement is the last stop in the movement of food through your digestive tract. It is made of what is left after your digestive system (stomach, small intestine, and colon) absorbs nutrients and fluids from what you eat and drink. It's also called stool or feces. Stool passes out of the body through the rectum and anus.
Sometimes a bowel movement isn't normal. Diarrhea happens when stool passes through the large intestine too quickly. Constipation occurs when stool passes through the large intestine too slowly. Other abnormalities with bowel movements may be a sign of a digestive problem.
NIH: National Institute of Diabetes and Digestive and Kidney Diseases
References and abstracts from MEDLINE/PubMed (National Library of Medicine)