Penicillin is an example of a DRUG, which is a type of medication used to treat and prevent disease. It was discovered in 1928 by Alexander Fleming, a Scottish biologist and pharmacologist, and is one of the most widely used antibiotics in the world. Penicillin is derived from a fungus and works by inhibiting the growth of bacteria. It is used to treat a variety of bacterial infections, including strep throat, pneumonia, and skin infections.