Informed consent is a central concept of contemporary medical ethics. Clinicians and medical researchers are under an obligation to inform patients and research subjects about the nature, purposes, risks, and side effects of proposed courses of action (and, if relevant, a specification of the risks of not acting in the suggested way). A vast body of literature has been produced, over the past 30 years or so, about the nature, justification, scope, and limits of informed consent. Here we will focus on what informed consent is, how it came to have a central place in medical ethics, and then briefly introduce some of the main problems and issues with informed consent.