Final answer:
The House Committee on Un-American Activities (HUAC) was formed by Congress to investigate alleged Communist influence. Witnesses were subpoenaed and required to testify, and those who refused often faced consequences such as losing their jobs or being placed on a blacklist.
Step-by-step explanation:
The House Committee on Un-American Activities (HUAC) was formed by Congress to investigate alleged instances of subversion and disloyalty among federal employees and influential private citizens. The committee gained national attention in 1947 when it began investigating Communist influence in Hollywood. Witnesses were subpoenaed and required to testify, and those who refused or invoked the Fifth Amendment often faced consequences such as losing their jobs or being placed on a blacklist.