A molar is one of the large, flat teeth at the back of your mouth designed for grinding and crushing food. While your front teeth bite and tear, your molars do the heavy work of chewing. Run your tongue along your teeth toward the back: those wide, bumpy teeth are your molars.

Most adults have twelve molars, three on each side of the upper and lower jaws. The broad, ridged surface of each molar works like a millstone, mashing food into smaller pieces that are easier to swallow and digest. When you chew a carrot or grind up a piece of steak, your molars are doing most of the work.

Children start losing their baby teeth around age six, and the first permanent molars often appear around this same time, which is why they're sometimes called six-year molars. The last molars to come in are the wisdom teeth, which typically arrive in the late teenage years (though many people have them removed because there isn't enough room in their jaws).