Heat is an important part of reactions of different sorts and without heat we would not be able to make as much as we have in the world of today. There are different types of heat reactions and as is obvious by the name of the reaction, heat is required in all of them. There are primarily two types of heat reactions- those where heat is given out and those where heat is absorbed. The former is known as an exothermic reaction while the latter is known as an endothermic one. Both reactions are used in different industries for different purposes.
Where heat is given out, those types of heat reactions are, as stated earlier, known as exothermic reactions and an example of such a reaction is the process of the mixture of sodium with chloride. The process is used to produce sodium chloride which is known as salt to the ordinary lay man. Another example of these types of heat reactions is the process of combustion. You know how your fuel runs on an engine? If you pop open the hood and start the car, you can feel the engine producing heat and you can feel the heat itself. If you put a thermometer near it you would see the temperature rising as well.
Even if you turn on gas to put on a heat in the winters, you can feel the heat being given out- again these are exothermic reactions. Any reaction where heat is given out is known as an exothermic reaction and exothermic reactions are all around us though we just do not notice them enough.
Then those types of heat reactions where heat is absorbed are known as endothermic and for the process to take place, of course, heat from outside is required to be absorbed. Usually these types of heat reactions are used to break, what are known as, chemical bonds. The process of cremation, the burning of the body of a dead person, requires heat to be absorbed by the body so that it can be burned, decomposed and turned to ashes. Numerous chemical bonds in the body are destroyed so that the body is decomposed. Another process where heat is absorbed in order to break a chemical bond is that of cooking. In order to cook raw food, you need heat so that the food is cooked from the inside and is edible. Similarly, baking is also endothermic- heat is required by the foods so that they can be baked and made successfully.
This is why these types of heat reactions are known to reduce the nutritional value of foods in some cases. Even the simple process of evaporation is an endothermic reaction- heat is absorbed by a liquid and the liquid then breaks down and evaporates into the air.
These are just some types of heat reactions. If you look around you, you would see that there are different types of heat reactions all around you that take place on a daily basis.