The term "Red Scare" refers to two distinct periods of intense anti-communism in American history, primarily during the early 20th century. The first Red Scare, occurring after World War I, was characterized by fear of communist influence following the Russian Revolution and included widespread paranoia, government suppression, and the Palmer Raids targeting suspected radicals. The second Red Scare, after World War II, involved fears of Soviet espionage and communist infiltration, leading to McCarthyism, where individuals were blacklisted and persecuted based on alleged communist ties. Both periods marked significant civil liberties restrictions in America.