An exothermic reaction releases energy in the form of light or heat to its surroundings, contrasting with endothermic reactions which absorb energy. The term "Exo" denotes "release," and "thermic ...

Handwarmers are an example of an exothermic reaction. They release heat into their surroundings. However, exothermic reactions don't always release heat, sometimes the energy is released as light.

A presenter-led science video investigating exothermic and endothermic reactions, with Dr Maggie Aderin-Pocock and Dr Alex Lathbridge.