A layover is a break in a journey, often imposed by the schedule of the traveler. The term is most commonly used in the context of airplane travel, but people using buses, trains, and ferries can also experience layovers. As a general rule, most travelers try to avoid layovers, although in some cases an extended one will be deliberately scheduled. A trip itinerary usually details the included layovers, along with their lengths.
In the most common scenario, a layover happens because a traveler is traveling between two points which are not directly connected. For example, someone might need to travel between Burlington, Vermont, and Los Angeles, California. There are no direct flights between these locations because there is not enough consumer demand, so the passenger must first travel to a larger city, such as New York or Chicago, and then take another flight to Los Angeles.
This is an illustration of the hub and spoke model which has been adopted by many airlines. These airlines have one or more central hubs with large numbers of flights every day, and they route passengers through these hubs rather than providing direct flights. If a passenger needs to travel directly between two hubs, like London and Los Angeles, no layover would be required. While it can be frustrating for passengers, this system makes transport much more efficient, and can lower the overall operating costs of an airline or freight company.
A layover can be rather grueling and frustrating, especially if a passenger is taking a trip with multiple legs. Even domestic travel can sometimes require as many as four changes of plane, train, or bus, and unlucky passengers may find themselves enduring layovers which are rather long. Typically, passengers stay in the airport or station during a layover, since the time period is usually not long enough to explore the neighboring community. Passengers can also be severely penalized for missing the next leg, so they want to stay close to the station.
If a passenger knows that he or she will need to experience a layover, a deliberately long layover might be scheduled. Typically this type of layover is overnight, allowing the passenger to book a room and explore the city or visit friends, albeit briefly. It can be tricky to plan a trip with this type of layover, especially in the case of airplane travel, since the passenger will need to clear security twice. Some airlines discourage this behavior for this reason.