Utilitarianism is a theory of ethics, or one of multiple ways to decide what is right and what is wrong. Someone who follows the theory of utilitarianism is called a utilitarian. Utilitarians believe that the distinction between whether an action is right or wrong should be decided by comparing how much comfort and happiness the action causes, with how much pain and suffering occur as a result. For example, in a utilitarian's mind, murdering somebody is not always wrong. Instead, it depends on the circumstances. If murdering somebody will somehow save many people from suffering, and the suffering that the murder victim will endure is less than the measure of the happiness caused to those other people, then murder is the right thing to do.