Effective altruism is a philosophy and social movement that applies evidence and reason to determining the most effective ways to improve the world. Effective altruism encourages individuals to consider all causes and actions, and then act in the way that brings about the greatest positive impact, based on their values. It is this broad, scientific approach that distinguishes effective altruism from traditional altruism or charity. While a substantial proportion of effective altruists have focused on the nonprofit sector, the philosophy of effective altruism applies much more broadly, e.g., to prioritizing the scientific projects, companies, and policy initiatives which can be estimated to save and improve the most lives. Notable people associated with the movement include philosopher Peter Singer, Facebook cofounder Dustin Moskovitz, Oxford based philosopher William MacAskill and researcher Toby Ord.