Anesthesia

The loss of feeling or sensation. It may be accomplished without the loss of consciousness, or with partial or total loss of consciousness. {Healthline}

Local anesthetics are agents that cease nervous impulses without rendering unconscious. They may be either rapidly-acting, unstable ester-based or slower, more stable amide-based.

General anesthetics includes cessation of pain impulse, unconsciousness, relaxation, memory block, maintenance of homeostasis (stable body function).
In operation, general anesthetic may be inhaled or administered through IV. Current inhaled agents are nitrous oxide ("laughing gas"), halothane (a halogenated hydrocarbon), enflurane, isoflurane (halogenated ethers), sevoflurane, desflurane (fluorinated ethers), and xenon (rarely). Current intravenous agents are thiopental, methohexital (which bind GABA receptor sites of the brain), propofol, etomidate (which have shorter durations), ketamine (an alternative to PCP), diazepam (marketed as Valium), and midazolam.