An autoimmune disorder occurs when the body's immune system mistakenly attacks its own healthy cells, tissues, or organs. This happens because the immune system, which is designed to protect the body from infections and diseases, fails to distinguish between foreign invaders and the body's own components. As a result, various parts of the body can become inflamed or damaged. There are many types of autoimmune disorders, including rheumatoid arthritis, lupus, and multiple sclerosis. Symptoms can vary widely depending on the specific disorder and the areas affected, but they often include fatigue, pain, and swelling. Treatment typically focuses on managing symptoms and reducing immune system activity.