Coumarin is first identified in 1820, and is an oxygen heterocyclic compound famous for its vanilla like or freshly mowed hay fragrance. Coumarin contains benzene ring and a α-pyrone fused together. Coumarin is generally found in many plants like tonka seeds, sweet clover grass, lavender and licorice. It is also present in fruit bearing plants like apricots, cherries, strawberries and cinnamon. Artificial production of Coumarin started since 1820 and has been used in manufacture of flavoring and perfume since 1868. Coumarin is produced as pesticides by the plants and artificially it is used to manufacture amalgams like anti coagulants and rat poison. Coumarin is the responsible for the smell mown grass and hay. When Coumarin is fermented it generates dicoumarol which present in sweet clover. This is very strong anticoagulant which forms base of rat poison, which creates hemorrhage in the rodents. This discovery in modern days scientists used as anti clouting agent.