Southwest Airlines uses an open seating policy, meaning seats are not assigned in advance. Instead, passengers choose their seats upon boarding. Southwest boards passengers in three groups and based on the Southwest Airlines Seat Selection Policy boarding pass number, which is assigned during check-in. The earlier you check in, the earlier your boarding group, which increases your chances of securing a preferred seat. Southwest offers EarlyBird Check-In for a fee, which automatically checks you in 36 hours before your flight, improving your boarding position. Passengers with specific seating needs or those traveling with children may board earlier with pre-boarding privileges.