A Red Scare is a form of moral panic provoked by fear of the rise, supposed or real, of leftist ideologies in a society, especially communism and socialism. Historically, "red scares" have led to mass political persecution, scapegoating, and the ousting of those in government positions who have had connections with left-wing to far-left ideology. The name is derived from the red flag, a common symbol of communism and socialism.
The term is most often used to refer to two periods in the history of the United States which are referred to by this name. The First Red Scare, which occurred immediately after World War I, revolved around a perceived threat from the American labor movement, anarchist revolution, and political radicalism that followed revolutionary socialist movements in Germany and Russia during the 19th–early 20th century.
The Second Red Scare, which occurred immediately after World War II, was preoccupied with the perception that national or foreign communists were infiltrating or subverting American society and the federal government.