An open-jaw ticket is an airline ticket in which a traveler returns to the airline from a city other than the one in which they arrived, or in which the final destination is not the same as the original departure city. The trip between these two cities is then made over land, sea or with a separately booked flight. The path-lines between the airports form an open angle, rather than a closed loop, and the angle resembles an open jawline. This is also sometimes called an ARNK (Arrival Unknown). It is sometimes also called Multi-city, but that might also be a ticket with three flight legs forming a closed loop.
In some cases, this type of arrangement is needed for boat cruises that do not return to the departure city. In other cases, the traveler wishes to explore between two points and not have to worry about using time to return to the arrival city. For example, a traveller might fly from London to Bangkok, travel around Thailand by public transport and fly back home to London from Phuket. Another example would be a traveler flying from New York City to San Francisco but then returning to Washington, D.C. Open-jaw tickets are a flexible and relatively inexpensive way of flying, as such tickets are almost always less expensive than purchasing two round-trip flights between the destinations visited.
Another market commonly traveled, under an open-jaw itinerary, is the one of local one-way tours. Take, for example, a tour of Florida, where a traveler flying into Jacksonville, Orlando, or Miami rents a car or joins a bus tour at their arrival airport, and returns the car or ends the tour in the town from which they'll be flying home.
An alternative for an open jaw ticket is a continent pass.