Milk-supplying protuberance associated with extant eutherian as well as marsupial mammals but not with monotremes.

The teat provides a means of latching on by mammals to the source of their . This presumably improves the efficiency of transfer or uptake as well as more to the 's body such as in terms of stimulation of further .

Depending on the mammal, the number of teats can range from two to many more than ten, with the total number of teats roughly corresponding to maximum for a given species and half the number of teats approximating the average number of offspring produced per .

While the concept of teat is not identical to that of either nor , there often is one-to-one correspondence between teat and in those female mammals possessing teats.

Video (Except for the "Sample use only" across the screen, this is a nice overview from hormones to positions)