It's called the
métro for short, but was originally conceived as the
chemin de fer métropolitain (metropolitan railway), then officially known as the CMP (
compagnie du chemin de fer métropolitain de Paris, the Paris metropolitan railway company). Since 1949, it's been run by the RATP (
Régie autonome des transports parisiens, the autonomous public transportation authority). I'm sure you were curious.
A southbound train pulls into the station early on a Friday afternoon. Not a very busy time of day for this station.
This station is on the number 12 line, which runs between Front Populaire on the north side of the city to the Mairie d'Issy on the south side. The northern endpoint used to be at Porte de la Chapelle, as many of us old-timers will remember, but the line was extended in 2012. Another extension is planned for 2019 further north to the Mairie d'Aubervilliers. This station, Assemblée Nationale, is right smack in the middle of the city on the left bank.
The system currently has 16 lines operating with four more planned, along with numerous line extensions. There are over 300 stations in the system. The
métro is the central part of a sprawling regional transit network that includes suburban rail lines that connect to the center city (the RER), light rail lines in the inner suburbs (
les tramways), and city buses (
les autobus).
I got most of the technical information in this post from the Wikpedia entry for the
métro. And, if you didn't know, I spent much of my professional career in public transportation and am somewhat of a transit nerd. I could go on (and on) about the
métro system, but I will spare you that.