Radicals were political activists or ideologists who sought extreme or fundamental changes to part or all of the social and political order. Historically, radicals wanted reforms such as expanding the vote to larger parts of the population (including working classes), abolishing privileges of aristocracy and wealthy landowners, and establishing governments based on majority rule rather than elite control. The term originated in 18th century England and became associated with movements advocating for parliamentary reform, broader democracy, republicanism, and social reforms. Radicals often positioned themselves on the left wing of liberalism and were key figures in various 19th-century social and political reform movements across Europe and America. More specifically:

• In England, radicals pushed for drastic electoral reforms and universal manhood suffrage starting in the late 1700s and 1800s.
• In France, radicals were associated with republicanism, social reform, secularism, and were seen as heirs to the ideals of the French Revolution.
• Radicalism includes a range of ideologies advocating for civil liberties, social justice, redistribution of wealth, secularism, and anti-monarchism.

The essence of radicalism is a desire for root-level reform rather than incremental change, sometimes including the use of extreme methods to achieve these reforms.