It also kills hookworms and roundworms. All with a few drops in one spot. Revolution is a chemical called selamectin. It's in the class of chemicals known as avermectins, and a derivative of dormectin. Pfizer discovered selamectin in 1991, and began clinical development and field development of it in 1992, specifically for dogs and cats.
Revolution is interesting because of how it works.
It's applied topically, to the skin. It's absorbed through the skin, and into the bloodstream, where it travels throughout the system. It's excreted through the intestinal tract, where it kills heartworms and the intestinal nematodes. It's selectively redistributed to the sebaceous glands, where it comes out and goes into the hair follicle, and then to the skin over the whole body. That's where it kills the fleas and sarcoptic mites, and prevents flea eggs from hatching.