The currency of Turkey is Turkish Lira (TL). And for the small decimals Turkey will use Kurus (KR) same as Cents and they will be all in coins. Currency can be exchanged at airports, banks, and exchange booths – of which there are many. Banks open mainly Monday to Friday from 8.30 to 12.00pm and 1.30pm to 5.00pm. Most bank branches have ATMs which accept Cirrus and Plus and an ATM’s can also be found at the airport. Major credit cards are widely accepted. Travellers cheques can be exchanged at banks and hotels. US$ or Euros are preferred. Post Offices in the larger towns will sometimes change currency and travellers cheques for a much lower commission than banks.
The unit of Turkish money is the Turkish Lira (Türk Lirasi, TL). On January 1, 2009, new banknotes were introduced.
From January 1, 2005 until December 31, 2008, Turkey's currency was called the New Turkish Lira (Yeni Türk Lirasi, YTL or TRY). As of January 1, 2009, the "New" (Yeni) has been dropped. The currency is again simply the Turkish Lira. Please note that Yeni Turk Lirasi (YTL) is not in currency anymore.
It's best to wait until you get to Turkey to exchange money for Turkish Liras. Exchange rates outside of Turkey are usually not as good as those inside Turkey.
The Turkish Lira is divided into 100 kurus (kurush; that's koo-ROOSH). Here's how the new 2009 notes/bills look.
Although you can sometimes use foreign currencies (euros are best, US dollars are good, UK pounds sterling are accepted in some places) for larger transactions, and using non-Turkish currency is legal, you will want to use TL most of the time.
The easiest way to get cash liras is to stick your home bank card or credit card into a Turkish ATM (bancomat/cashpoint, cash machine). Travelers' checks are a much less efficient way.
You can exchange foreign-currency cash at a Currency Exchange Office (Döviz Bürosu).
The best currencies to carry for changing to TL are, again, euros, US dollars, and UK pounds.
Please check the current rate through the office web site of the Turkish Central Bank.