Here's why Southwest is assigning seats — and what it means for customers

Southwest will start selling assigned seats, marking a major shakeup of a signature policy that has set the low-cost carrier apart from airlines for half a century. The new policy, announced Thursday, will make flying Southwest look and feel remarkably different for customers. 

The shift will affect how customers of the discount carrier select seats and board planes. Southwest passengers, including longtime fans of the open seating policy, will also be able to choose different types of seats for a price, including those offering more legroom. These changes could affect ticket costs across the board, according to experts, although Southwest has not addressed pricing or indicated that regular seat costs will change. 

Some experts are cheering the move, saying it amounts to an improvement for both passengers and the airline.