What did black listting refer to during the McCarthy witch hunt for communist?

During the McCarthy witch hunt for communists in the 1950s, "blacklisting" referred to the practice of denying employment to individuals in the entertainment industry who were suspected of having communist ties or sympathies. Those placed on a blacklist faced widespread ostracism, making it nearly impossible to find work in Hollywood and other sectors. The practice was part of a broader campaign led by Senator Joseph McCarthy to root out alleged communist influence in American society, often based on little evidence and resulting in severe consequences for many lives and careers.