Endothermic and exothermic reactions are two types of chemical reactions. In an endothermic reaction, the energy is absorbed from the surroundings, resulting in a decrease in temperature. On the other hand, in an exothermic reaction, energy is released into the surroundings, resulting in an increase in temperature. In other words, endothermic reactions require energy to be put in, while exothermic reactions release energy. An example of an endothermic reaction is photosynthesis, while combustion is an example of an exothermic reaction.