Aspirin, or acetylsalicylic acid, is a common drug, originally made by the Bayer company in Germany as a synthetic version of salicylic acid, which is found in the bark of willow trees and was once used as a pain reliever.

In addition to reducing pain, aspirin is used to treat inflammation and fevers. It also prevents blood from clotting and improves circulation, and can be an effective treatment for the prevention of heart attacks and strokes.