Endothermic reactions take in energy from the surrounding environment. The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to get colder. If the products contain more energy than the reactants, heat is taken in or absorbed from the surroundings and the change is called an endothermic reaction.
Some examples of endothermic reactions are:
The reactions between ethanoic acid and sodium carbonate
The reaction between ammonium nitrate and water.
The thermal decomposition of calcium carbonate in a blast furnace