Cleft lip and palate result from the failure of anatomical structures forming the face and oral cavity to properly unite or fuse during fetal development. Depending on the degree of this condition, clefts are classified as complete or incomplete:
* Complete Clefts: Refer to situations where the union of structures did not occur at all. In the lip, it extends up to the nose; in the palate, it affects the uvula, soft palate, and hard palate entirely.
* Incomplete Clefts: Are situations where structures partially united but fusion was not completed. In the lip, it may appear as a slight notch or a partial cleft not reaching the nose; in the palate, it is usually limited to the uvula and soft palate.

Lip clefts are also classified as unilateral (on the right or left side) or bilateral (on both right and left sides), due to the position of the fusion lines in the upper lip.

In summary, the main types of clefts are:
* Unilateral Cleft Lip: Incomplete or Complete
* Bilateral Cleft Lip: Incomplete or Complete
* Cleft Palate: Incomplete or Complete