Yes, you will always be assigned a seat on a commercial flight before you board, regardless of whether you choose one yourself. If you opt not to pay for a specific seat, the airline's computer will automatically assign one to you, typically at the time of check-in. On some carriers, particularly "Ultra Low-Cost Carriers" like Frontier or Spirit, if you don't pay, your seat is randomly generated, often resulting in a middle seat. On full-service airlines, if you check in early, you might still have the chance to pick from the remaining "unoccupied" seats for free. It is a common misconception that you might be "bumped" if you don't have a seat assignment; while overbooking does happen, your seat assignment status is not the primary factor in who is moved to a later flight. As long as you have a confirmed ticket and check in on time (usually at least 45-60 minutes before departure), the airline is legally obligated to provide you with a seat or compensate you if the flight is truly oversold and they cannot fit you on board.