Coming from the planet Cybertron, the Transformers are divided into two factions, the heroic Autobots, led by Optimus Prime, and the evil Decepticons, led by Megatron. They are able to "transform", rearranging their bodies into common or innocuous forms, including vehicles (the most commonly known form), devices or animals. Beyond that, they can displace mass (i.e. shrink and expand), combine with one another, and apply synthetic flesh. This ability to transform is reflected in the Transformers taglines "More Than Meets the Eye" and "Robots in Disguise". All Transformers stories and characters, in a range of media, have been based around this core concept since their debut in 1984.