A thermal insulator essential is an object that reduces heat transfer between objects in either thermal contact or in a range of radioactive influence. In other words – a good thermal insulator is anything that does not conduct heat, or heat up fast.
For example, even air is considered to be a good thermal insulator because air disperses the heat through the atmosphere, making it difficult for heat to pass through air.
Plastics, wood, cork, and some fabrics are also good thermal insulators because they do not conduct heat easily. This is because they contain weak molecular bonds in disorderly arrangements.