Left-wing politics supports social equality and egalitarianism, often in opposition to social hierarchy. It typically involves a concern for those in society whom its adherents perceive as disadvantaged relative to others (prioritarianism) as well as a belief that there are unjustified inequalities that need to be reduced or abolished (by advocating for social justice). The term left-wing can also refer to "the radical, reforming, or socialist section of a political party or system".
The political terms "Left" and "Right" were coined during the French Revolution (17891799), referring to the seating arrangement in the French Estates General: those who sat on the left generally opposed the monarchy and supported the revolution, including the creation of a republic and secularization, while those on the right were supportive of the traditional institutions of the Old Regime. Use of the term "Left" became more prominent after the restoration of the French monarchy in 1815 when it was applied to the "Independents". The word "wing" was appended to Left and Right in the late 19th century, usually with disparaging intent and "left-wing" was applied to those who were unorthodox in their religious or political views.
The term was later applied to a number of movements, especially republicanism during the French Revolution in the 18th century, followed by socialism, communism, anarchism and social democracy in the 19th and 20th centuries. Since then, the term left-wing has been applied to a broad range of movements including civil rights movements, feminist movements, anti-war movements and environmental movements, as well as a wide range of parties. According to former professor of economics Barry Clark, "[leftists] claim that human development flourishes when individuals engage in cooperative, mutually respectful relations that can thrive only when excessive differences in status, power, and wealth are eliminated".