People generally grow 2 sets of teeth in a lifetime. These 2 sets being the primary teeth and the permanent teeth.
Otherwise known as baby teeth, deciduous teeth, and milk teeth, primary teeth usually start growing at 6 months and completely fall off at age 13. Children typically grow 20 baby teeth before their adult teeth start to grow into place.
Adult teeth, on the other hand, are referred to as permanent teeth because this set of pearly whites are naturally designed to last a lifetime. Adults usually grow 32 permanent teeth which develop between the ages of 6 and 14 years.