BTS Skytrain

Bangkok can boast one of the most up to date Mass Transit Systems in the world, the overground version is called the "Skytrain". It as two lines which connect most of the centre of Bangkok with the northern part of the system.
Most of the central located tourist spots like Siam Square, Sukhumvit Road and Patpong are on the BTS network. All of the Stations are above street level, you get your ticket from an Automatic Telling Machine, if you have'nt the correct change, there are Booth's where you can change Notes. There is a number key for which ever Station you want to go to, just press the numbered button, put in the amount that it tells you and out the ticket pops. You then go through the turnstile and go to the platform you need.
There is a train every five minutes, and when you get on you will notice how clean and graffiti free the trains are. The cost of the ride ranges from 20 - 50bht, or you can buy a 100bht a day ticket that gives you unlimited travel for the whole of that day, and when you have finished with this card and it is only early evening, give yout ticket to the first person you see walking up the BTS Stairs, it will make their day.
One thing to remember however, is there are many Kiosk's on the Staion's, unfortunately you cannot eat or drink on the platform, so dont buy anything, unless you plan to drink it later.