United Airlines is a major United States airline headquartered in Chicago, Illinois. It is the world's third largest airline when measured by revenue. United Airlines operates a large US domestic and international route network, with an extensive presence in the Asia-Pacific region. United Airlines is also one of the founding members of the Star Alliance, the world's largest airline alliance with a total of 28 member airlines.
MileagePlus is the loyalty program of United Airlines. There are 04 tiers in MileagePlus, namely, Premier Silver, Premier Gold, Premier Platinum and Premier 1K. All Premier members are eligible for Premier Access, which allows them to use exclusive check-in and security lines, as well as priority boarding and baggage retrieval.
To join United Airlines' Mileage Plus, you can simple register online here.