General anesthetics are drugs that produce reversible loss of sensation and consciousness. They are administered by anesthesiologists to facilitate surgery. The key effects are loss of sensation including pain, unconsciousness and amnesia, loss of reflexes, immobility, and muscle relaxation. Anesthetics have stages including analgesia, delirium, and surgical anesthesia. Common general anesthetics are inhalational gases like nitrous oxide and volatile liquids like sevoflurane and intravenous drugs like propofol and thiopentone sodium. They work by potentiating GABA receptors or inhibiting NMDA receptors. Inhalational anesthetics are delivered via gases or vapors and include nitrous oxide, halothane, sevoflurane and isoflurane.