A thermal insulator is a material used in industry, characterized by its high thermal resistance. It establishes a barrier to the passage of heat between two media that would naturally tend to equalize in temperature, preventing the heat from passing through the separators of the system of interest with the surrounding environment.
In general, all materials offer resistance to the passage of heat, that is, they are thermal insulators. The difference is that the ones in question have a very high resistance, so that small thicknesses of material present sufficient resistance to the intended use. One of the best thermal insulators is a vacuum, in which heat is only transmitted by radiation, but due to the great difficulty in obtaining and maintaining vacuum conditions, it is rarely used. In practice, air with low humidity is mostly used, which prevents the passage of heat by conduction, thanks to its low thermal conductivity, and by radiation, thanks to a low absorption coefficient.
