Frontier Airlines provides incredibly cheap tickets that simply include the trip. Airlines will charge a certain amount to you for seat selection. The cost will depend on the location and type of the frontier airlines seat selection on aircraft. In case you are not selecting your seat in advance, you will get an auto assigned seat at the time of check-in your seat number will be there on your boarding pass. If you enjoy the concept of a la crate discounts yet value legroom above all else while traveling, you should be aware of how Frontier Airlines' seating arrangement operates. https://www.airlinereservationwindow.com/frontier-airlines-seat-selection/