An adult human typically has 32 teeth.
That full permanent set includes 8 incisors, 4 canines, 8 premolars, and 12 molars. The teeth are divided evenly between the upper jaw, or maxilla, and the lower jaw, or mandible, with 16 in each. Incisors cut food, canines tear it, and premolars and molars crush and grind it.
The number 28 causes confusion because it describes the permanent teeth without the four third molars, commonly called wisdom teeth. Wisdom teeth often erupt between ages 17 and 25, but they may remain impacted, fail to develop, or be removed. For that reason, many adults have 28 visible or retained teeth even though the standard full count is 32.
Humans first develop a set of 20 primary, or baby, teeth. These are gradually replaced by permanent teeth beginning in childhood. Extra teeth are called supernumerary teeth, while having fewer than the usual number is known as hypodontia.