外科, or "surgery," is a branch of medicine that focuses on diagnosing and treating diseases, injuries, and deformities through surgical procedures. Surgeons perform operations to remove, repair, or replace tissues and organs, often using specialized instruments and techniques. This field encompasses various specialties, including 心脏外科 (cardiac surgery), 神经外科 (neurosurgery), and 整形外科 (plastic surgery). Each specialty addresses specific medical conditions, requiring extensive training and expertise. Surgical interventions can range from minor procedures to complex operations, all aimed at improving patient health and quality of life.