Paris ticket system
To travel on the RATP transport system in Paris, since 12th of June 2019, you can buy the Navigo Easy Pass, which will replace the single paper tickets sale by 2020.
Update: June 2019
This new Pass costs 2 EUR and you can upload tickets on it: single tickets, airports shuttle, and all packages sold by RATP. This Navigo Easy Pass is of course re-useable and you can keep it for the next time you visit Paris.
Where can you buy the Navigo Easy Pass?
In all tram/bus/subway stations for the amount of 2 EUR.
Be careful, the Navigo Easy Pass is only available for transport lines in Paris itself and in the close suburbs. If you want to travel further in the suburbs, for example to Versailles Castle, you’ll have to buy the old version of subway tickets (no need to buy a Pass).
The Navigo Easy card can be shared between passengers, but not for the same journey at the same time.