Why is heat transfer necessary​

It is necessary for keeping body temperature of humans as well as keeping things such as animals, plants, etc alive. We need heat transfer to allow things to live basically. Say a dog gets frostbite or something along those lines, the dog wouldn’t naturally have enough heat to survive so we would have to transfer heat into the dog so it could survive.

It is crucial for designing powers systems that involve heat.

Is there a picture of the diagram?