Q: What is a stopover?
A: A stopover on an international itinerary is any break in your air travel for more than 24 hours except at the destination.

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Q: Do I pay more for a stopover or open-jaw?
A: Typically no additional mileage is required but additional taxes or fees are often payable (especially in UK with high Air Passenger Duty). Extra mileage will often be required if an open-jaw or stopover adds a higher cost region into the itinerary. Also awards wholly within CONUS, Canada and Alaska (formerly known as Series 0 awards) require additional mileage (10K miles) for a stopover of >4 hrs.