US-based United Airlines (UA) is the world's largest airline when measured by the number of destinations served. A member of the Star Alliance, United flies non-stop to about 375 airports worldwide. These include about 75 domestic destinations, as well as points in 70 countries in North America, South America, Europe, Asia, Africa and Oceania. United's fleet features a variety of two-, three- and four-cabin configurations including First Class (known as Global First or United First on international and domestic flights respectively), Business Class (known as Business First or United Business), United p.s. (short for Premium Service) on certain transcontinental flights, Economy Plus Class and Economy Class. Premium cabin passengers can use the airline's United Club lounges, which can be found in about 40 airports.