* Exothermic reactions are chemical reactions where energy is released into the surroundings, usually in the form of heat. This makes the surroundings warmer.

* Endothermic reactions, on the other hand, require energy from the surroundings to occur. These reactions make the surroundings colder.

Examples of exothermic reactions:

* Burning fuel: Burning wood, gas, or oil releases heat and light.

* Explosions: These are rapid exothermic reactions that produce a lot of energy in a short amount of time.

* Rusting: The process of iron reacting with oxygen to form rust releases heat.

Key takeaway: Any process that releases energy is considered exothermic.