The color of them also defines the type of route ( orange for local loop, green for local area, blue for cross city and red for long distance)

There are some details on the Seoul city website, I can’t find the link at the moment.

Or you can plan your route directly from here :
http://bus.congnamul.com/SeoulRouteWebApp/view_english/map.jsp

It’s well worth knowing some good local buses that go to stations on other subway lines.
Transferring from one subway line to another can take ages going up and down stairs etc.
So if the local bus takes you straight to a station on that line, instead of walking to your local station then changing to the other line you can save a lot of time.

Also you can save money if you have to go somewhere to pick something up and come back: You get up to 30 minutes to make a transfer and it does not matter if the route is the exactly the same as the way you went, you just pay for any extra the distance beyond 5km.

Plus you get to see a whole lot more of Seoul. And the way the drivers swing them round the corners it’s like a free fairground ride too!

The most important thing though is : DON’T FORGET TO SWIPE YOUR T-MONEY CARD ON THE WAY OUT. If you fail to do that you get charged double fare on your next journey.

Happy bus riding.