Individual ticlkets for the downtown area are valid within zones 1 and 2. Each can be used for a single trip on the Metro, RER, bus, or tram. The price is 1.30 euros for one ticket or 9.60 for 10 tickets (called a Carnet). Children from 4 to 11 years old can have half price discount for a Carnet, say 4.80 euros for 10 children tickets. Individual tickets to Paris suburbs are priced based on the distance traveled.
The Carte Mobilis is a daily ticket that allows unlimited travel on the Metro, RER, bus, RATP, ADATRIF, APTR, and SNCF suburban network. It excludes the Orlybus, Orlyval, Roissybus, Roissyrail and Orlyrail. Price is based on area of coverage, for Zone 1 - 3, it is 6/7 euros.
3-The Paris Visite
The Paris Visite is a bit more expensive than the Mobilis. It allows you to discover Paris and its surroundings. With it, you enjoy unlimited travel on all public transit systems, including: the Metro, RER, buses, tram, Montmartre funiculaire, Montmartobus, Noctambus, suburban trains, and private buses from ADATRIF and APTR. According to the zones you choose (1-3 to 1-8), you can travel as far as Disneyland Paris, Versailles, or the airports. Passes can be valid for 1, 2, 3, or 5 days, beginning any day of the week. They are half price for children between 4 and 11 years old. Travel on the RER and SNCF suburban trains is in first class cabins. The pass also allows you to receive discounted entry into 30 of Paris' museums. No photograph is required to obtain this pass.
The Carte Orange can be the best choice for visiting Paris for more than three days if your visit starts towards the beginning of the week. For example, the weekly ticket covering zones 1 to 3 is 18.35 euros, whereas the 3-day Paris Visite pass for the same zones is 18.25 euros. The Carte Orange weekly pass is valid from Monday through Sunday. Between Monday and Wednesday, you may purchase a ticket for the current week. Between Friday and Sunday, you may purchase a ticket for the coming week. The monthly pass is valid from the first to the last day of each month.