Exothermic and endothermic reactions

During endothermic reactions, heat is taken in from the surroundings. E.g. thermal decomposition. On the other hand, exothermic reactions produce heat. E.g. burning fuels and burning candles.

Endo thermic is heat taken in and exothermic is heat given off. — Think of a group of thermometers entering a sauna where they take in heat (endothermic). Later on, the thermometers exit and go outside where they give out heat (exothermic).

Entering = Endothermic = taking in heat

Exiting = Exothermic = giving out heat