Ryanair offers you the option to purchase reserved seats or opt for free seats, which are assigned randomly after check-in. Passengers who choose ‘random seat allocation’ can check in between 72 hours and 2 hours before the flight departure time.
If you purchase a seat at the time of booking, during check-in, or at any point leading-up to your flight, you can choose where to sit and that seat will be reserved for you. Online check-in opens 60 days before the scheduled departure time if you have purchased an allocated seat.
The price of a reserved seat depends on where you choose to sit on the aircraft.