İstanbul’s taxis are yellow lighted with TAKSI signs on top. Taxis can easily be found all around the city. In addition there are many taxi stops around the city near most crowded places, hotels, restaurants and touristic spots where they can be acquired easily by phone. There is also a mobile application “taximetre” where you can easily call a cab and calculate the approximate fee for the trip.
Source: icvb.org.tr
