Istanbul has a good public transport system with lots of new metro, rail and tram lines opening since the Millenium. There are many out-of station transfers that require you to pay another fare, to get where you are going. However, if you put some effort into it, you can avoid taxis and not walk too much. An easy way to cope with the system is to download city-smart applications such as “trafi”. Google maps also show updated transport options between two points of travel.
There is an extensive bus system, including city-run and private buses, as well as one high-speed Metrobüs line; an extensive light rail system including six Metro (underground) lines, four Tramvays (aboveground), three Fünikülers (ascending/descending), two mini-lines called Teleferik, and the Marmaray (underwater) lines; and the ferries which travel the Bosphorus.
Buying an ‘’Istanbulkart’’ is a good idea if you are in Istanbul for more than a day or two, and intend to use public transport. Basically it pays itself if you take more than 4 times of bus, metro, ferry etc. This is a plastic card that looks like a credit card. It can be used as a ticket on buses, trams, suburban trains, metro, some cross-Bosphorus ferries, and even some public toilets. You touch the Istanbulkart to a reader when you get on the bus or enter the tram/metro platform. You can buy or refill them at designated booths located at any major bus, tram, to metro station, as well as some other places such as newspaper stands close to bus stops.