Ryanair is now operating all of its flights with allocated seats.
The Irish carrier moved to a fully allocated seating policy on Saturday.
It means that passengers can select a seat when booking or when checking-in online.
Premium seats occupy rows 1-5, 16, 17, 32 and 33 and cost €10/£10 for priority boarding, extra legroom and/or faster disembarking.
For €5/£5, standard seats occupy rows 6-15 and 18-31 and allow passengers to pre-select a preferred window or aisle seat or ensure that they sit together. Priority boarding can be added for a €2/£2 supplement.
Passengers who do not wish to pre-select their seats can check-in during the period from seven days to two hours prior to their flight and they will be assigned an allocated seat at no cost.
Ryanair has been rolling out a number of customer service improvements over recent months (see news, December 9).
Ryanair spokesperson Robin Kiely said: "All Ryanair customers can now enjoy allocated seating on all flights, the latest customer service improvement to be rolled out.
"We are listening to our customers and responding, so that they can continue to enjoy the lowest fares and most on-time flights, but can also benefit from our recent improvements to our industry leading customer service, including a second free small bag carry-on bag, easier website access, a “My Ryanair” registration service, 24 hour grace periods, “quiet flights” and reduced bag fees, with further improvements set to be rolled out over the coming weeks and months."