A taxiway is a path for aircraft at an airport connecting runways with aprons, hangars, terminals and other facilities. They mostly have a hard surface such as asphalt or concrete, although smaller general aviation airports sometimes use gravel or grass.
Busy airports typically construct high-speed or rapid-exit taxiways to allow aircraft to leave the runway at higher speeds. This allows the aircraft to vacate the runway quicker, permitting another to land or take off in a shorter interval of time. This is usually accomplished by making the exiting taxiway longer, thus giving the aircraft more space in which to slow down, before the taxiways’ upcoming intersection with another (perpendicular) taxiway, another runway, or the ramp/tarmac.
Source: Official Forum