Simple: adjacent fingers or toes are joined by soft tissue and skin only
Complex: the bones of adjacent fingers or toes are fused together (this is extremely rare)
Complete: the skin is joined the entire length of the digits
Incomplete: the skin is joined partially up the digit, usually to the first joint
Fenestrated: the skin is joined for most of the digit, but there is a gap in the middle of the joined skin
Polysyndactyly: there is an extra digit webbed to an adjacent digit.