An insulation or insulator, is a barrier of non-conductive material around electrical conductors and other circuit-components like resistors, capacitors, IC etc.
Insulator is an object made of non-conductor or bad-conductor substance., to ensure current flow in only the desired and correct pathway. As non-conducting substances, many-kind of subtances are used such as polymers ( plastic like P.V.C, Polystyrene, Cellophane, bakelite, etc , natural rubber, gutta-percha, synthetic rubber, paper, wood), Ceramics (Porcelain,china-clay, mica), etc. chosen in different shapes and thickness, depending upon the voltage-limits, temperature, mechanical disturbance etc. In cases of un-insulated (bare) wires; the dry air acts as insulator. The Circuit-boards' substrate is an insulator are commonly made up of complex mixture of insulating material (such as FR4). Synthetic Epoxy-resins widely used in different semiconductor devices.
In capacitors, an insulating layer between 2 parallel-plates used as di-electric, a term of static-electricity used to describe any substance between 2 charged particles, through-which the electrostatic attraction works.
Commonly, whitespace used as the symbol for insulation.