Chronic Fatigue Syndrome (CFS) is a complex disorder characterized by extreme fatigue that lasts for at least six months and is not improved by rest. This fatigue often worsens with physical or mental activity, leading to significant limitations in daily activities. The exact cause of CFS is unknown, but it may involve a combination of factors, including viral infections, immune system issues, and hormonal imbalances. Symptoms of CFS can vary widely and may include sleep disturbances, cognitive difficulties, and muscle or joint pain. Diagnosis is primarily based on patient history and symptom evaluation, as there are no specific tests for CFS. Treatment typically focuses on managing symptoms and improving quality of life through lifestyle changes and supportive therapies.