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 early 2026, Southwest will modify its cabins to offer some rows 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 and appear for the first time in travel aggregators' search results.