USA There are lots of different insulators. Fiberglass insulates your home and is very itchy. Another insulator is paper. When you buy something that is cold, they put it in a paper bag to keep it cold. Another insulator is leaves.
Leaves keep animals warm.
Leaves also keep the ground and plants warm. Squirrels build nests with leaves. Leaves keep sprouts from dying in the spring. Snow can keep the ground from freezing. Fiberglass keeps our house from getting cold.