Warm blooded animals also known as Homeotherms. These animals maintain their body temperature constant whatever be the outside temperature. They generate their own heat when in cooler surrounding and cool themselves when in hotter environment. They generate heat by eating varieties of food which gives them energy for keeping body temperature constant.
In the hotter environment, warm blooded animal sweat to lose heat by evaporation. In the colder environment they shiver to prevent loss of heat and generate more heat. Even in mammals body is covered with fur or hairs and in birds with feathers to keep them warm in winter.
Examples: All birds and mammals.