The agents or media which can transfer the pollen grains for pollination are called the agents of pollination.
Air, water, animals and insects are the common agents of pollination.
Pollination by air: Light and dry pollen grains are carried by air to the other plants.
Pollination by water: Pollen or the male flower is carried by water current towards the female flower to pollinate.
Pollination by insects: The bright colors of corolla and nectar attract the insects and pollen grains stick to the body of the insect which facilitates pollination as it approaches another flower.
Pollination by animals: Animals and birds interact with the flowers helping with pollination.