**1. Introduction**

Postoperative pain is more than just the feeling of pain in the wound and is associated with damage to the tissues and organs involved in the surgical invasion. Postoperative pain consists of nociceptive pain, inflammatory pain, and neuropathic pain. In addition, psychogenic pain can also contribute to postoperative pain. Surgeries involving deep pain in bones, joints, or the spine and surgeries involving visceral pain, such as laparotomy, cause more severe postoperative pain than craniotomies or surgeries of the chest wall, abdominal wall, or skin, which cause only superficial pain. Postoperative pain is most severe during the first 24 hours following the surgery and often subsides thereafter, but in some cases, the pain may persist. In recent years, endoscopic surgeries with small skin incision account for the majority of planned surgeries. Although injuries to the skin and fascia have reduced, visceral injuries remain the same, which is why analgesics are necessary. In this section, we will discuss the changing approach to postoperative pain with the evolution of surgery and anesthesia.
