We are warm blooded animals, so are all other mammals, to a certain extent, and birds. However warm blood is not really the question, many reptiles have blood far warmer than ours, but only on hot days. In fact, blood temperature is merely a reflection of body temperature. The important thing about mammals and birds is that they maintain a constant internal temperature. Endothermy means generating heat internally.
All mammals are endothermic and most are homeothermic.
Some mammals cannot always maintain a constant temperature within. Most bats are unable to maintain a constant temperature and cool down considerably when they sleep or rest. Rat Heterocephalus glaber , from Africa. This unique mammal has lost the the ability to regulate its body temperature endothermically. This does not effect their lives because they live underground in an environment with a very stable temperature regime.