In Turkey the mains voltage is 220 Volt. You may need a power adapter for all your electronic equipment, if in your country another mains voltage is used.
Four- and five-star hotels often provide North American-style 120 volts, 60 Hz flush-mounted sockets) for North American flat-prong plugs. Check your appliances before leaving home to see what you'll need to plug in when you travel in Turkey.
Many appliances with their own power adapters can be plugged into either 110-120-volt or 220-240-volt sockets/points and will adapt to the voltage automatically.
If it reads that way, it can operate on either 110-125 or 220-240 voltage. If it says something like "INPUT: 100-125V", then it can't run on Turkey's 220-240 volts and you'll need to bring a transformer (also called a power or voltage converter)..
Many Turkish hotels have plug adaptors that they lend to guests. In Istanbul, there are several electrical shops in Eminonu on the streets between Sirkeci Station and the Main Post Office.