There are two types of public buses in Istanbul; those run by the private sector and those run by the city-owned İETT, and they can be differentiated by their colors. Privately run buses are blue-green with yellow non-electronic destination signs while İETT-run buses come in many colors like red and blue, with newer green ones and red double-deckers as well.
The Metrobüs is a long hybrid bus running in its own lane separated from all other traffic and thus saves a lot of time. The Metrobüs runs between Avcılar and Kadıköy on the Asian Side via Bakırköy, Cevizlibağ, which is just out of old city walls near Topkapı Gate, and Mecidiyeköy.
Most bus lines operate between 6AM and midnight. Service is generally reduced after 10 PM. There are some major lines that operate 24 hours. Note that after midnight, buses cost two tickets pp rather than the usual one.