Metabolism is a variety of biochemical and biophysical functions that are performed to maintain life. At its' core, metabolism is a sum of all chemical reactions in an organism, a process of breaking down energy and gaining energy back in a constant cycle of life. There are different complex molecular ways of gaining energy, but for complex organisms, they are sorted into two: exothermic and endothermic. Birds and mammals are endothermic, meaning they maintain their own body temperature, while reptiles, are exothermic, meaning they maintain their body temperature through their outside environment
