On occasion, the Senate may go into what is called a secret or closed session. During a closed session, the chamber doors are closed, cameras are turned off, and the galleries are completely cleared of anyone not sworn to secrecy, not instructed in the rules of the closed session, or not essential to the session. Closed sessions are rare and usually held only when the Senate is discussing sensitive subject matter such as information critical to national security, private communications from the president, or deliberations during impeachment trials.