Tokyo subway

I can't drive a car. I have a driver's license (it's convenient to have one as an official ID), but the last time I drove is more than 10 years ago and I've already lost my ability to drive. Why? Because of the convenience of using public transportation. It's almost always on time. I have never counted how many stations there are in Tokyo (nor I wish to do that), but I'll just say, A LOT. Here is just a map of subway. In addition to subways, here are another trains on ground as well.
You can download the English version of the map of subway from Tokyo Metro website: 
http://www.tokyometro.jp/en/subwaymap/pdf/routemap_en.pdf