BTS
Also known as "Bangkok Skytrain".
This is a train that is often used to travel around central Bangkok. At first glance, it looks like a Japanese monorail, but it is a regular track railway.
BTS is an acronym for Bangkok Mass Transit System Public Company Limited.
Thai people call it Rotfeifer.
(meaning train). The cost is around 25-45 baht.
During rush hours and weekends, the train is quite crowded, and you often have to wait for the next train without being able to board the train. There are two lines, Sukhumvit Line and Silom Line, and you can transfer between them at Siam Station.
route map
The green and yellow-green lines are BTS. Blue is the subway.