In their lifetime, humans have two separate sets of teeth. The first set are known by names like “temporary teeth,” or sometimes “baby teeth,” while the second set are known as “permanent teeth” or “adult teeth.”
In the standard person’s mouth, there are 20 temporary teeth and 32 permanent teeth. The reason we have temporary teeth before we get the permanent teeth is that when you’re young and still growing, the 32 big permanent teeth wouldn’t be able to fit in your mouth! Because teeth are helpful and needed for many things (including chewing and talking) we need the set of temporary teeth to use while waiting for the permanent ones to come in. When your mouth is ready to handle your permanent teeth, they slowly start to push the temporary teeth out of the way, and this is why you lose your baby teeth!