Pollination: The transfer of pollen from the anthers of a flower to the stigma of the same flower or of another flower. Pollination is a prerequisite for fertilization: the fusion of nuclei from the pollen grain with nuclei in the ovule. Fertilization allows the flower to develop seeds.
Normally there are two types of pollination :-
a) Self-pollination and
b) Cross pollination.
Some flowers will develop seeds as a result of self-pollination, when pollen and pistil are from the same plant, often (but not always) from the same flower.
Other plants require cross-pollination: pollen and pistil must be from different plants.