Energy

Energy is the capacity to do work or produce change. 

Energy exists in various forms, such as thermal, mechanical, chemical, electrical, and radiant energy, and can be transferred between objects or transformed from one form to another.

In the context of fire safety, energy is primarily concerned with thermal energy (heat), which is necessary for igniting and sustaining combustion.

Energy is a fundamental concept in physics and underpins many processes, including fire. For example, during combustion, chemical energy stored in fuel is converted into thermal energy (heat) and radiant energy (light), driving the chemical reactions that sustain the fire.