MileagePlus is the loyalty and frequent flyer program of United Airlines, one of the largest and most prominent carriers in the United States. Established in 1981, the program allows passengers to earn and redeem miles for a variety of travel-related benefits. Members can accrue miles not only through United Airlines flights but also through flights operated by Star Alliance member airlines and other program partners. MileagePlus offers a tiered structure with different elite status levels, including Premier Silver, Premier Gold, Premier Platinum, Premier 1K, and Global Services. Each tier provides escalating privileges such as priority boarding, lounge access, and bonus mileage earning. Members can use their accumulated miles for flights, upgrades, hotel stays, car rentals, and various other travel-related rewards. MileagePlus reflects United Airlines' commitment to rewarding customer loyalty and fostering lasting relationships with its frequent flyers.