There are two main categories of dragons: Chromatic Dragons and Metallic Dragons, but also a few who fall outside those categories, such as the Lignum. There are also some dragon-kin that aren't actually true dragons, such as Wyverns. Contrary to popular belief, far from all of these are aggressive or dangerous. Many just want to be left alone, and some are actually quite helpful. But they were also the reason for the Second Breaking, and humanoids often fear dragons to the point of fighting or enslaving them if they can.