An airline alliance is an aviation industry arrangement between two or more airlines agreeing to cooperate on a substantial level. Alliances may provide marketing branding to facilitate travelers making inter-airline codeshare connections within countries. This branding may involve unified aircraft liveries of member aircraft.
In 2015, Star Alliance was the largest with 23% of total scheduled traffic in revenue passenger miles (RPMs)/revenue passenger kilometres (RPKs), followed by SkyTeam with 20.4% and Oneworld with 17.8%, leaving 38.8% for others. In 2019, by number of passengers, Star Alliance was leading 762 million, followed by SkyTeam (630 million) and Oneworld (535 million).