Effective altruism (EA) is a 21st-century philosophical and social movement that advocates "using evidence and reason to figure out how to benefit others as much as possible, and taking action on that basis". People who pursue the goals of effective altruism, sometimes called effective altruists, may choose careers based on the amount of good that they expect the career to achieve or donate to charities based on the goal of maximising positive impact. They may work on the prioritization of scientific projects, entrepreneurial ventures, and policy initiatives estimated to save the most lives or reduce the most suffering.

Toby David Godfrey Ord is an Australian philosopher. In 2009 he founded Giving What We Can, an international society whose members pledge to donate at least 10% of their income to effective charities, and is a key figure in the effective altruism movement, which promotes using reason and evidence to help the lives of others as much as possible.