A cruise line is a company that operates cruise ships and markets cruises to the public. Cruise lines are distinct from passenger lines which are primarily concerned with transportation of their passengers. Cruise lines have a dual character; they are partly in the transportation business, and partly in the leisure entertainment business, a duality that carries down into the ships themselves, which have both a crew headed by the ship's captain, and a hospitality staff headed by the equivalent of a hotel manager.
Because of mergers and consolidations, a cruise line may also be a brand of a larger holding corporation. For example, as noted below, Carnival Cruise Line and Holland America Line are cruise lines within the larger parent corporation Carnival Corporation & plc. This industry practice of using the brand, not the larger parent corporation, as the cruise line is also followed in the member cruise lines in Cruise Lines International Association (CLIA); the listing of cruise ship sales, transfers, and new orders; cruise line market share; and the member-based reviews of cruise lines.
Cruise ships can cruise in oceans or rivers. The listing of cruise lines below includes separate lists for both areas. Cruise lines operating ocean and river ships can be found in both lists.