(this poster for sale)

How to use the Paris Metro subway system.

The Paris Métro first opened on 19 July 1900 with line #1

The Paris Métro is part of a 3,500 km public transport network (metro, bus and RER) 

The original and cool looking Art Nouveau entrances were designed by the architect Hector Guimard. 

I personally found the metro system clean, well lit and safe. It is a pretty cheap and fast way to get around Paris costing about $1.00 per ticket. The best way to buy tickets is to ask for a 'carnet' (T is silent)which is a packet of ten tickets. These tickets are also good on the RER (Réseau Express Régional within Paris) and Bus System as well! So with a pocket full of these tickets you can get on anything. They look like this...

front

back (has a magnetic strip on it)

The Paris Metro system is almost exclusively underground and is composed of fourteen lines.
Each line is designated by a number; #1 through #14 and each is color coded. 

Line #1 - Dark Yellow
Line #2 - Lavender
Line #3 - Light Sap Green
Line #4 - Dark Pink
Line #5 - Orange
Line #6 - Light Hinter Green
Line #7 - Light Pink
Line #8 - Dark Lavender
Line #9 - Dark Sap Green
Line #10 - Golden Ochre
Line #11 - Brown
Line #12 - Hunter Green
Line #13 - Blue
Line #14 - Dark Purple

Each line's direction is named by the final destination or terminal point of the line. For instance, one line I took often while there - the pink colored line #04 which had at the north end "Porte de Clignancourt" and at the south end "Porte D'Orleans". So when your  at the metro you first make sure you know toward what terminal point you are headed on the line you are taking because the entrances to the metro platforms take you to only one direction or the other. In this case either to the north bound train to "Porte de Clignancourt" or the south bound train to "Porte D'Orleans".

Almost all of the metro lines terminate at each end somewhere near the Boulevard Peripherique which is the loop highway around the city of Paris. In the central part of town there seems to be an entrance to the Metro within easy walking distance of everywhere with a total of 368 stations around the city 87 of which being interchanges between the different lines. So as long as you stay somewhere near an entrance (every building in Paris is within 500 meters) to a Metro Station you can get just about anywhere you want to go in ten to fifteen minutes.

At the entrance to a particular line and at the platform you will see a sign with the terminal point listed as well as any other lines you'll be able to connect to along the trail.

Looking at a map...
The elongated circle means that several metro lines connect at this large station and you can anticipate quite a walk between lines at these stations. The circles are stations where there is one or two lines. Once you are in the metro system, there is no extra cost for changing from one line to another. So to get anywhere in Paris from anywhere else you look for the connecting points where the line your taking connects with the line you need to get to your destination.