United Airlines is a major U.S. carrier that provides passenger air travel and air cargo services across a global network spanning six continents. The company sells tickets and ancillary services through united.com and its mobile apps, operates the MileagePlus loyalty program with co-brand credit card partnerships, and supports operations with large-scale digital systems. Headquartered in Chicago, it is part of publicly traded United Airlines Holdings (NASDAQ: UAL) and a member of Star Alliance.