In politics, a red flag is predominantly a symbol of left-wing ideologies, including socialism, communism, anarchism, and the labour movement. The originally empty or plain red flag has been associated with left-wing politics since the French Revolution (1789–1799). The red flag and red as a political colour are the oldest symbols of socialism.
Socialists adopted the symbol during the Revolutions of 1848. It was first used as the flag of a new authority by the Lyon Commune and Paris Commune in the aftermath of the Franco-Prussian War (1870–1871). The flag of the Soviet Union, introduced during the Russian Revolution, as well as the flags of many subsequent communist states, were explicitly inspired by the plain red flag. Many socialist and socialist-adjacent political parties, including those of democratic socialists and social democrats, have adapted and adopted a red flag as their symbol. The plain red flag was an official symbol of the Labour Party in the United Kingdom until the late 1980s. It was the inspiration for the socialist songs "The Red Flag" and "Bandiera Rossa".