An executive session is a portion of the United States Senate's daily session in which it considers nominations and treaties, or other items introduced by the President of the United States. These items are termed executive business; therefore, the session is an executive session. It can either be closed door or open door. Historically, as a courtesy to the President such sessions were always held behind closed doors, but this custom has been abandoned in modern times. The term "executive session" is still employed to refer to closed-door committee meetings, whether or not they are considering executive business.
More generally, an executive session is a term for any block within an otherwise public meeting (often of a board of directors) in which minutes are not taken, outsiders are not present, and the contents of the discussion are treated as confidential. (See In camera.)