Southwest Airlines Boeing 737-800 while on taxiing runway, before takeoff. This photo taken by Marco Dotti, he took a new livery of the airline anyway.
Southwest Airlines is world's largest low-cost carrier, founded in 1967 and headquartered in Dallas, Texas. The carrier has about 3,400 flights per day these are more flights than another giant US Airlines, such as American Airlines or Delta Air Lines. They transported most United States' domestic passengers. Based on 2014 statistics, they handled more than 133 million passengers and in 2015 they seems to pass United Airlines in terms of number of passengers. Entire Southwest Airlines fleet are Boeing 737 Series, currently they are waiting the newest Boeing 737 MAX Series. The carrier has nearly 700 active fleet and keep on increasing.