The first class and coach cabins are still separate on United Air Lines. A leading passenger and cargo airline, United serves destinations in some 30 countries from hubs like Chicago, Denver, Houston, Los Angeles, San Francisco, Tokyo, and Washington, DC. The airline, which also offers regional services via subsidiary United Express, operates a fleet of some 700 mainland aircraft. In addition, it leads the Star Alliance, a marketing and code-sharing group that includes Continental and Lufthansa. (Code-sharing lets airlines sell tickets on one another's flights, offering passengers more destinations.) United is a subsidiary of United Continental Holdings, which acquired Continental in 2010.