Define anesthesia, and differentiate topical, local, regional, general, and surgical anesthesia.
Anesthesia refers to the loss of sensation, typically induced for medical procedures. Topical anesthesia numbs only the surface area where it's applied (e.g., numbing gel for dental procedures). Local anesthesia blocks sensation in a specific area (e.g., lidocaine injection for a dental filling). Regional anesthesia numbs a larger area or region of the body (e.g., epidural for childbirth). General anesthesia renders the patient unconscious and insensitive to pain (e.g., for surgery). Surgical anesthesia is a subset of general anesthesia specifically tailored for surgical procedures.