There are two different sets of molars that humans get within their lifetimes. Baby molars are the ones that fall out and that are then replaced by the permanent molars.
Molars are the biggest and roughest of all the teeth. The purpose of the molar is to help the tongue when swallowing food. The tongue helps push the food to the molars. The molars grind the food particles until the person can swallow. Wisdom teeth are considered the third set of molars. It is believed that wisdom teeth once aided in chewing as well. The size of modern human mouths are too small to accommodate the wisdom teeth. They are often extracted in adulthood.