The separation of two bodies by inserting between them material that is a poor conductor of sound, heat, light, or electricity. For example, the insulating coating on an electrical cable prevents the current flowing in the cable from affecting objects beyond the cable; the soundproofing insulation on the walls of a broadcasting or recording studio prevents sound entering the studio from outside; the vacuum layer in a vacuum flask prevents heat passing outwards from a hot liquid or inwards to warm a chilled liquid.