Paris has an excellent public transport system, divided into
five zones radiating out from the centre; ticket prices vary
according to the number of zones required. Public transport
consists of buses, an underground metro, and express trains (RER).
Taxis are also available. The easiest way to get around is on the
metro and the subways are generally safe at all times. It is
possible to transfer between the metro and the RER trains at no
extra cost. The bus system is also extensive, but is slower, less
frequent and best used for getting to destinations the metro does
not cover. A nightbus service, Noctilien, covers the city between
1am and 5.30am. Taxis are readily available and can be hailed or
caught at taxi ranks. Vélib' bicycle rentals are also
popular for getting round town: pick up a bike at one of over 1,200
stations and return it at any other.