Demand-Responsive Transit (DRT) is a flexible transportation service that adapts to the specific travel needs of its users, and is typically shared among users. Instead of following fixed routes and schedules, DRT services are typically booked in advance and operate within a defined area. DRT started decades ago as Dial-a-Ride or paratransit, which serves a specific population (e.g. elderly) or with a specific technology (e.g. phone calls for day-ahead reservations), but has been generalized recently to serve general populations and more advanced communication technologies (e.g., wireless and internet for real-time reservations). As a form of transit, it can serve multiple passengers on a journey, though the service may use anything from passenger cars to small buses to provide the service. It may also include deviated route service, in which an otherwise fixed-route service may make unscheduled stops within a corridor or service zone to pick up or drop off passengers.

Microtransit is a subset of DRT, often characterized by the use of new technologies to optimize and manage the public transit service with a specific focus on either population, spatial coverage or coordination with general public transit. It blends aspects of traditional public transit and private ride-hailing services, offering shared rides that are dynamically routed. Microtransit is generally operated within defined service zones or along a corridor, often with designated stops at key destinations like employment centers or transfer points to other transportation services [1].