A state of being able to tolerate an operation or procedure. The patient is either asleep / unconscious or a certain part of the body has been made numb (anaesthetised) so that no pain is felt.
General Anaesthesia: The patient is asleep and unconscious, the airway has been secured and the patient is ventilated.
Regional Anaesthesia: A certain part of the body has been made numb (pain and temperature can't be felt) to be able to carry out an operation or procedure.
Sedation: The patient is asleep during a procedure and usually does not remember. Sedation is often used for Regional Anaesthesia