Real-time ridesharing (also known as instant ridesharing, dynamic ridesharing, ad-hoc ridesharing, on-demand ridesharing, and dynamic carpooling) is a service that arranges one-time shared rides on very short notice. This type of carpooling generally makes use of three recent technological advances: GPS navigation devices to determine a driver's route and arrange the shared ride Smartphones for a traveler to request a ride from wherever they happen to be Social networks to establish trust and accountability between drivers and passengers These elements are coordinated through a network service, which can instantaneously handle the driver payments and match rides using an optimization algorithm. Like carpooling, real-time ridesharing is promoted as a way to better utilize the empty seats in most passenger cars, thus lowering fuel usage and transport costs. It can serve areas not covered by a public transit system and act as a transit feeder service. Ridesharing is also capable of serving one-time trips, not only recurrent commute trips or scheduled trips.