Diarrhea is defined as having 3 or more loose or liquid stools per day. It is commonly caused by viral, bacterial, and parasitic infections transmitted through contaminated food or water. The main symptoms are an increased frequency of loose stools, dehydration, and weight loss. Treatment involves oral rehydration therapy with oral rehydration solution and continued feeding. For severe cases, intravenous fluids and antibiotic treatment may be needed. Prevention relies on improved sanitation, hygiene, food safety, and access to clean water.