Ryanair DAC is an Irish ultra low-cost carrier founded in 1984. It is headquartered in Swords, Dublin, Ireland and has its primary operational bases at Dublin and London Stansted airports. It forms the largest part of the Ryanair Holdings family of airlines and has Ryanair UK, Buzz, Lauda Europe, and Malta Air as sister airlines. It is Ireland's biggest airline and in 2016 became Europe's largest budget airline by scheduled passengers flown, carrying more international passengers than any other airline.