Southwest Airlines is the largest domestic air carrier in the United States by passengers boarded. Southwest operates nearly 800 aircraft in an all-Boeing 737 fleet. Despite offering some longer routes and a few perks for business travelers, the airline predominantly specializes in short-haul, leisure flights operated in a single, open-seating cabin configuration in a point-to-point network. In late 2025, Southwest will modify its cabins to offer some seats with extra legroom and will update its ticketing process and merchandising to offer assigned seats and more fare categories including a basic economy class that will more directly compete with other airlines' offerings.