The hammer and sickle (Unicode: "☭") is a symbol meant to represent proletarian solidarity, a union between agricultural and industrial workers. It was first adopted during the Russian Revolution at the end of World War I, the hammer representing workers and the sickle representing the peasants.

After World War I (from which the Russian Empire withdrew in 1917) and the Russian Civil War, the hammer and sickle became more widely used as a symbol for labor within the Soviet Union and for international proletarian unity. It was taken up by many communist movements around the world, some with local variations. Following the dissolution of the Soviet Union at the end of the Cold War, the hammer and sickle remains commonplace in Russia and other former Soviet republics. In some other former communist countries, as well as in countries where communism is banned by law, its display is prohibited as part of decommunization policies. The hammer and sickle is also commonplace in later self-declared socialist states such as Cuba, China, North Korea, Vietnam, and Laos.