Autonomous Parisian Transportation Administration RER
Time : Lines vary, but typically daily, 6:00 a.m. to 1:00 a.m.
The RER is the commuter railway train system, which is similar to the metro. The primary difference between the RER and the metro is that the RER extends further into the surrounding regions of Paris rather than just beyond the city limits as the metro does. The RER also makes fewer stops, so it can transport people more quickly to their destinations. There are five express trains from which to choose, any one of which can move people across the city within 20 minutes. Tickets cover specific zones within the city and the regions, so be sure to purchase a ticket that covers the zones you need — or check with a ticket agent — to avoid a fine for riding further than your ticket covers.
Andy’s Notes :
Your ticket is required to exit the RER station, so hold onto it until you have reached and departed your final RER station.