a generic drug is a drug that uses the same active ingredients than another drug, which is already on the market. this second drug often uses a brand name. the german company bayer developed an analgesic based on acetylsalicylic acid in the late 19th century. it marketed the drug as "aspirin". the drug is no longer under copyright, and anyone can produce a drug with the same active substances, but they may not call that drug aspirin, because that is a trade name. very often, such drugs are marketed with the name of the main active substance, and the name of the company producing the drug. in most cases generic drugs are cheaper to buy than the branded alternatives.