A cruise line is a company that operates cruise ships. Cruise lines are distinct from passenger lines which are primarily concerned with transportation of their passengers: instead, cruise lines are primarily in the leisure entertainment business, some of which occurs at the destination but a great deal of which takes place aboard ship. Cruise liners typically have two separate staffs: the crew under the captain and a hospitality staff under the equivalent of a hotel manager. Among cruise lines, some are direct descendants of the traditional passenger lines, while others were founded from the 1960s on specifically for cruising. The business is extremely volatile; the ships are massive capital expenditures with very high operating costs, and a slight dip in bookings can easily put a company out of business. Cruise lines frequently sell, renovate, or simply rename their ships just to keep up with travel trends. A wave of failures and consolidation in the 1990s has led to many lines existing only as “brands” within larger corporations, much as a single automobile company produces several makes of cars. Brands exist partly because of repeat customer loyalty, and also to offer different levels of quality and service. For instance, Carnival Corporation owns both Carnival Cruise Lines, whose former image were vessels that had a reputation as “party ships” for younger travellers, but have become large, modern, and extremely elegant, yet still profitable, and Holland America Line, whose ships cultivate an image of classic elegance. Currently the five largest cruise line operators in the world are Carnival Corporation & plc, Royal Caribbean Cruises Ltd., Star Cruises, MSC Cruises and Louis Cruises.