There are three types of breech presentation: complete, incomplete, and frank.
Complete breech is when both of the baby's knees are bent and his feet and bottom are closest to the birth canal.
Incomplete breech is when one of the baby's knees is bent and his foot and bottom are closest to the birth canal.
Frank breech is when the baby's legs are folded flat up against his head and his bottom is closest to the birth canal.
There is also footling breech where one or both feet are presenting.