Diarrhea is a loose, watery bowel movement and is not usually a serious problem in the U.S. It can occur due to illness, intestinal problems, food poisoning and many other factors. It usually goes away on its own, but you should drink plenty of fluids during a bout.
For more information, visit: https://www.niddk.nih.gov/health-information/digestive-diseases/diarrhea