Crowding
Crowding of the teeth occurs when there is a lack of space for all the teeth to fit normally within the jaws.

Spacing
Spacing of the teeth, the opposite of crowding, is an excess of available space, resulting in gaps between the teeth. 

Protrusion
Protrusion of the teeth, also known as overjet, is when the lower teeth are too far behind the upper front teeth.

Open Bite
An open bite is an insufficient vertical overlap of the teeth. 

Deep Bite
A deep bite is an excessive overlap of the upper front teeth to the lower front teeth. 

Under Bite
An underbite is when the lower jaw is excessively larger or more developed than the upper jaw, or a combination thereof.