When the pollen grains of an anther do not germinate on the stigma of the same flower, then such a flower is called self-sterile or incompatible and such condition is known as self-incompatibility or self-sterility.
The transference of pollen grains shed from the anther to the stigma of the pistil is called pollination. This transference initiate the process of seed formation. Selfpollination is the transfer of pollen grain shed from the anther to stigma of pistil in the same flower. But in some flower self-pollination does not lead to the formation of seed formation because of the presence of same sterile gene on pistil and pollen grain.