Didactyly
Didactyly (from Greek δι- di- "two") or bidactyly is the condition of having two digits on each limb, as in the Hypertragulidae and two-toed sloth, Choloepus didactylus. In humans this name is used for an abnormality in which the middle digits are missing, leaving only the thumb and fifth finger, or big and little toes. Cloven-hoofed mammals (such as deer, sheep and cattle – Artiodactyla) have only two digits, as do ostriches. Monodactyly
Monodactyly (from Greek μόνος monos- "one") is the condition of having a single digit on a limb, as in modern horses and other equidae (though one study suggests that the frog might be composed of remnants of digits II and IV, rendering horses as not truly monodactyl) as well as sthenurine kangaroos. Functional monodactyly, where the weight is supported on only one of multiple toes, can also occur, as in the theropod dinosaur Vespersaurus. The pterosaur Nyctosaurus retained only the wing finger on the forelimb, rendering it also partially monodactyl. As a congenital defect
Among humans, the term "five-fingered hand" is sometimes used to mean the abnormality of having five fingers, none of which is a thumb. Syndactyly
Syndactyly (from Greek συν- syn "together") is a condition where two or more digits are fused together. It occurs normally in some mammals, such as the siamang and most diprotodontid marsupials such as kangaroos. It occurs as an unusual condition in humans. Polydactyly
Polydactyly (from Greek πολυ- poly- "many") is when a limb has more than the usual number of digits.
Clinodactyly
Clinodactyly is a medical term describing the curvature of a digit (a finger or toe) in the plane of the palm, most commonly the fifth finger (the "little finger") towards the adjacent fourth finger (the "ring finger"). It is a fairly common isolated anomaly which often goes unnoticed, but also occurs in combination with other abnormalities in certain genetic syndromes, such as Down syndrome, Turner syndrome and Cornelia de Lange syndrome. In birds
Anisodactyly
Anisodactyly is the most common arrangement of digits in birds, with three toes forward and one back. This is common in songbirds  and other perching birds, as well as hunting birds like eagles, hawks, and falcons. This arrangement of digits help with perching and/or climbing and clinging. This occurs in Passeriformes, Columbiformes, Falconiformes, Accipitriformes, Galliformes and a vast majority of other birds. Syndactyly
Syndactyly, as it occurs in birds, is like anisodactyly, except that the third and fourth toes (the outer and middle forward-pointing toes), or three toes, are fused together, as in the belted kingfisher (Megaceryle alcyon). This is characteristic of Coraciiformes (kingfishers, bee-eaters, rollers, and relatives). Zygodactyly
Zygodactyly (from Greek ζυγος, even-numbered) is an arrangement of digits in birds and chameleons, with two toes facing forward (digits 2 and 3) and two back (digits 1 and 4). This arrangement is most common in arboreal species, particularly those that climb tree trunks or clamber through foliage. Zygodactyly occurs in the parrots, woodpeckers (including flickers), cuckoos (including roadrunners), and some owls.