With pollination non-ecologists usually think of honey-bees. As a matter of fact they're not as important as is thought. Wild plants don't depend on domestic bees for their pollination.
Many plants need to be pollinated to be able to grow seeds. Each plant species has its specific way of being pollinated. Some are pollinated by the wind, which is called anemophily. Others are pollinated by animals, this case is called zoophily. According to what animals pollinate, one can distinguish further: Entomophily is pollination by insects (wild bees, flies, beetles ...), ornithophily is pollination by birds (in the Mediterranean according to the current state of knowledge only the shrub Anagyris foetida), chiropterophily is pollination by bats.
Some plants pollinate themselves (examples: wheat, oats, barley, but not rye). Sometimes cultivated plants need to be pollinated by humans because their original pollinators do not live in that area.
Pollination in case of zoophily is a benefit for both the plant and the animal. Usually the animal receives food from the plant, often nectar, sometimes (as with poppies) only part of the pollen (which bees need to feed their larvae). Many wild bees are highly specialized on single plant species.
Anemophily is most common with grasses and trees that are very frequent in their habitat. Zoophilous plants usually have coloured flowers so that the animals find them easily. The flowers are so-to-speak the organs for external exchange with the animals.