Aspirin (acetylsalicylic acid), an organic compound that does not occur in nature, was first synthesised in 1899. 
In 1897, scientists at the drug and dye firm Bayer began investigating acetylated organic compounds as possible new medicines, following the success of acetanilide ten years earlier. Two years later, Bayer created acetylsalicylic acid, which they marketed around the world under the brand name "Aspirin". The drug was sold widely in the first half of the twentieth century, both by Bayer and by competing drug manufacturers. The name "aspirin" was so widely used that Bayer lost (or sold) the rights to the trademark in many countries.
Aspirins popularity declined after the development of acetaminophen/paracetamol in 1956 and ibuprofen in 1962. In the 1960s and 1970s, John Vane and others discovered the basic mechanism of aspirins effects, while clinical trials and other studies from the 1960s to the 1980s established aspirin's efficacy as an anti-clotting agent that reduces the risk of clotting diseases. Aspirin sales revived considerably in the last decades of the twentieth century, and remain strong in the twenty-first with widespread use as a preventive treatment for heart attacks and strokes.