When chemical reactions occur, energy is either released or consumed during the reaction.
Exothermic reactions are chemical reactions that release energy.
Example:
Burning a candle is an example of an exothermic reaction because energy is being released during the reaction in the form of heat.
Endothermic reactions are chemical reactions that absorb energy.
Example:
When an egg is cooked over a stove the reaction taking place is endothermic. The reaction absorbs the heat energy that is being produced by the stove burner.