Insulation is material that isolates a physical property. Usually this refers to either:
- Electrical insulation which prevents electricity from going where it isn't wanted.
- Thermal insulation which prevents heat from going where it isn't wanted.
Often materials that make good electrical insulators also make good thermal insulation, but there are exceptions. There is also insolation, which is the amount of sunlight striking a particular area.
Figure 1. Electrical insulation on a wire.
Figure 2. Thermal insulation for a house.