Aspirin is the trade-mark of Bayer Pharmaceuticals for their preparation of acetylsalicylic acid. It is one of the most commonly used drugs in the world and the trade-mark has now become synonymous with the drug.
The usefulness of salicylic acids in the treatment of pain have been known since ancient times. However, it had until the 19th century been practically impossible to produce them in therapeutically useful quantities or to deal with their toxic side effects.
Modern aspirin was first synthesized in 1853, but in impure form. Pure Aspirin was first isolated in 1859. In 1897, the Bayer company of Germany first came up with a new process for making Aspirin that allowed them to produce the drug for a mass market.
Aspirin has many pharmaceutical uses. It's primary purpose is the treatment of minor pain. However, it also has an anti-inflammatory effect, which makes it one of the primary drugs for the treatment of inflammatory diseases such as arthritis. It can reduce fever. It is also a blood thinner, and many patients with a history of heart disease or stroke are given aspirin once every two days to prevent clotting.