Diarrheal diseases are illnesses characterized by frequent, loose, or watery bowel movements. They can be caused by various factors, including infections from bacteria, viruses, or parasites, as well as contaminated food and water. Common symptoms include abdominal cramps, nausea, and dehydration, which can be serious, especially in young children and the elderly. Preventing diarrheal diseases involves practicing good hygiene, such as washing hands with soap and clean water, and ensuring food and water are safe to consume. Vaccines are available for some causes, like rotavirus, which can help reduce the incidence of severe diarrhea in children.