Although Paris is full of roads and streets for cars to drive on, most of my travels around the city have been on foot or via public transportation. This includes the bus system, metro and the RER. North Carolina does not have such a developed system of public transportation, which means I driving everywhere in a car when I am there. This is very different from my time in Paris--yes, the public transportation, here, has been very convenient!
The most commonly-used method of transportation in Paris is the metro, which has 303 lines and runs under the entire city. This is a good method of trasnportation for traveling shorter distances, just a few miles or so. However, the RER (Réseau Express Régional) is best for travelling from Paris to areas outside of Paris, as the RER covers the entire region rather than just the city. The RER has only 5 lines, so it is often used in a combination with the metro system.
As a student, I have a special card that I use to access public transportation without buying a ticket, for a discounted price. This card makes the metro even more convenient for me, which means I use this form of transportation practically every day.