Define pollination ?give difference b/w autogamy & allogamy ?

Pollination is the process of transfer of pollen grains from the stamens to the ovules of the ovary. The process of pollination is an interchange between flower and agent. This was first introduced in the 18th century by Christian Konrad Sprengel. The process of pollination is important in agriculture as fruits are a product of fertilization, which is a result of pollination. 

Self Pollination Definition  Self pollination takes place when the pollen from one flower pollinates the same flower or other flowers of the same individual. Self pollination is  a form of pollination which can occur when a flower has both the male and the female gametes, that is the stamens and the carpel or pistil.

Self Pollinating Fruit Trees are Apricots, Figs, few varieties of Peaches, some varieties of Plum like Stanley, Green Gage, Italian Prune and also some varieties of Apple are self pollinating. 

Self Pollinating Flowers are Flowers like Rose (Rosa spp.), food crops like beans, peppers tomatoes, Orchids, Violets, Sweet Peas, also self pollinate.

Cross Pollination Definition

Cross pollination is also known as allogamy. Cross Pollination occur when pollen grains are transferred to a flower from a different plant. The plants that undergo cross pollination often have taller stamens than their carpels. They use mechanisms to ensure that the pollen grains are spread to other plants' flowers. The process of cross pollination requires the help of abiotic or biotic agents like wind, water, insects, birds, bats, snails and other animals as pollinators.