There are two kinds of bus:
In this category you can find public and private buses, both make the same routes and have the same price. You'll be able to tell which are the public buses by the IETT logo, the state operator.
Tickets for the public buses can be bought in the stalls bearing either the "IETT" or "Bilet" logo, but this does not apply to all stops. The private buses, as well as accepting the same tickets s the public ones, also accept cash payment.
To know which bus you should take, you should ask at your hotel, as only the large and important stops have information about the routes.
The brave amongst you can see the different bus routes by clicking on the following web page:
These are small buses which pick people up on the street. There are no stops, and the destination is indicated on the front of the bus. If you want to get on, you just need to indicate so to the driver.
Payment is cash only.
Should I use the buses?
With the variety of public transport available in Istanbul, we don't recommend using the buses - although if you would like to, the most interesting route from a touristic point of view is the line that goes from Eminonü to Eyup.