People express opinions about which actions are right or wrong. Some may say that assisted suicide is right, while others say it is wrong. But what are people doing when they make moral statements? Are they asserting something? Or, on the contrary, are they only expressing emotions and wishes? There are also further questions that depend on the answer to that one: whether there is truth in morality; whether it already exists in the world and is only encountered by us, or whether we instead invent it; whether there are moral facts, and how we can recognize those facts. This introduction to metaethics explores the nature of morality. It illuminates morality from the points of view of philosophy of language, metaphysics, and epistemology. The book thus provides an overview of the various theories of metaethics. At the same time, it argues for a robust moral realism.