Saliva (commonly referred to as spit) is an extracellular fluid produced and secreted by salivary glands in the mouth. The enzymes found in saliva are essential in beginning the process of digestion of dietary starches and fats. These enzymes also play a role in breaking down food particles entrapped within dental crevices, thus protecting teeth from bacterial decay.


Source: https://en.wikipedia.org/wiki/Saliva