If Ryanair cancels your flight, you are protected under UK261 (for flights from the UK) or EU261 regulations. First, you have the right to choose between a full refund of your ticket or being rerouted to your destination as soon as possible, which includes being put on a flight with a competing airline if Ryanair cannot fly you within a reasonable timeframe. Second, if you are stranded overnight or for several hours, Ryanair is legally obligated to provide "Duty of Care," which includes hotel accommodation, transportation between the airport and the hotel, and vouchers for food and drinks. Third, you may be entitled to fixed financial compensation ranging from £220 to £520 (€250 to €600) per person, depending on the distance of the flight and how much notice you were given. You are generally ineligible for compensation only if the cancellation was due to "Extraordinary Circumstances" beyond the airline's control, such as severe weather or air traffic control strikes. It is highly recommended to keep all receipts for out-of-pocket expenses and to file your claim directly through the Ryanair website to ensure you receive the full amount mandated by law without third-party commission fees.