Reflex Sympathetic Dystrophy (RSD), now commonly known as Complex Regional Pain Syndrome (CRPS), is a chronic pain condition that typically affects the limbs after an injury or surgery. CRPS is characterized by intense, persistent pain that is disproportionate to the initial injury. Other symptoms include swelling, changes in skin color and temperature, and abnormal sweating. The condition is believed to involve abnormal responses of the peripheral and central nervous systems. Treatment options focus on pain management and improving function, and may include medications, physical therapy, nerve blocks, and in severe cases, surgical interventions. Early diagnosis and treatment are crucial for better outcomes.