An operation is a medical procedure involving incision, with instruments. It is performed for repair of damaged tissue, for instance after trauma. It is also done to arrest the progress of any pathology. The term surgery and operation can be used synonymously. A surgeon is a trained medical specialist who performs the surgery. An operation can be elective or an emergency. An elective operation is scheduled and performed for conditions that do not pose an immediate threat to the patient. An emergency operation is performed immediately because of presence of a life threatening condition in a patient. Based on the degree of invasion, an operation can be minimally, moderately or extensively invasive. An operation is a sterile procedure that is performed in a sterile environment. It entails use of a multidisciplinary team. There is the surgeon, the anesthetist, the scrub nurse among others. During the procedure, the patient is given medication that makes them sleep. Most operations will involve a hospital stay for at least a few days and a recovery period of at least two weeks.