Operators of cruise ships are known as cruise lines. Cruise lines have a dual character; they are partly in the transportation business, more over in the leisure entertainment business. In cruise ships which have both a crew headed by the ship's captain, and a hospitality staff headed by the equivalent of a hotel manager.
Historically, the cruise ship business has been volatile. The ships are large capital investments with high operating costs. A persistent decrease in bookings can put a company in financial jeopardy. Cruise lines have sold, renovated, or renamed their ships to keep up with travel trends. A ship which is out of service for routine maintenance means the loss of tens of millions of dollars. If the maintenance is unscheduled, it can result, potentially, in thousands of dissatisfied customers.
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.
Currently the five largest cruise line operators in the world are Carnival Corporation & plc, Royal Caribbean Cruises Ltd., Star Cruises, MSC Cruises, and Louis Cruise Lines. Louis Cruises has largely grown its fleet through purchasing older second- or third-hand ships, while the other four operators have largely constructed their own vessels and combined own the majority of the "megaships"