Materials through which heat can flow easily are called conductors.

Here's why:

* Conductors allow heat energy to pass through them readily. This happens because the atoms in these materials are closely packed and vibrate easily, transferring energy from one atom to the next. Examples include metals like copper, aluminum, and iron.

* Insulators are materials that resist the flow of heat. Their atoms are further apart, making it harder for vibrations to transfer energy. Examples include wood, plastic, and rubber.