Public transport is good in Paris and run by RAPT and a combination of bus, metro and trains. Tickets can be purchased in books or a number of passes for different zones can be used. If you wish to buy a public transport combinex with museum pass you will need a passport photo.
Paris batobus
Paris bus
Paris cycling
Paris Métro
Paris walking
Taxi
Taxis can be hailed form the streets or form one of the many taxi ranks. The taxi rate does vary according to the time of day and the zone and addition charges apply for pick ups at the train stations, airports, extra luggage and a fourth person.