Induction of anaesthesia is both the conduct of rendering a patient unconscious and the effect produced by adequate concentrations of an anaesthetic in the brain. It is followed by maintenance, emergence and recovery. Prerequisites are a suitable location, trained assistance, adequate monitoring, a range of drugs and devices, and dedicated emergency equipment. Induction can be intravenous or inhalational depending on clinical scenario or patient age. Rapid sequence induction is used to manage aspiration risk; other methods of induction are also described. Induction can be complicated by drug, airway, co-morbidity, or other factors addressable by professional guidelines or locally agreed protocols.