Celiac disease is a serious autoimmune disorder where eating gluten, a protein found in wheat, barley, and rye, triggers an immune response in the small intestine. This response damages the lining of the intestine, leading to problems absorbing nutrients from food. Symptoms include diarrhea, bloating, fatigue, and weight loss. It can also cause long-term complications like osteoporosis, infertility, and nerve damage. The only treatment is a strict gluten-free diet, which allows the intestine to heal and symptoms to improve. With proper management, people with celiac disease can lead healthy lives.