The currency is the Turkish lira (TRL). You can exchange currency in banks, hotels and exchange offices. Banks are open from 8:30 to 17:30, break from 12:30 to 13:30, day off on Saturday and Sunday. In resorts, banks are open seven days a week, on Saturday some exchange offices are open until 12:00. All banks exchange currency and conduct transactions with credit cards and travelers' checks. There are a large number of 24-hour ATMs.
Some tourists, especially those who come for shopping, want to know how much money can be brought into Turkey? The good news is that there is no limit on the amount. It does not matter in what currency you bring money, the Turkish policy of loyalty to foreign citizens-investors is obvious. The only important nuance is that if the amount of money you are bringing in exceeds the equivalent of 10 thousand USD, you will need to declare these funds when passing through customs control at the airport of arrival. The procedure does not take much time.
The Turkish currency is very unstable - the exchange rate changes almost every day. Do not accept banknotes below 5 thousand lira, since they are withdrawn from circulation due to inflation. In addition, dollars and euros are accepted almost everywhere, so it makes sense to exchange only a small amount - for small expenses.
If the question is: "What to bring to Turkey dollars or euros?", then the answer is simple. When choosing a currency before the trip, it does not really matter what currencies it will be - European or American. Exchange offices and banks will easily change any amount in either of these two currencies. Moreover, hotels, restaurants and bars will gladly take tips in dollars or euros, without exchanging them for lira. Some souvenir shops, vegetable stalls and even minibuses at resorts will be happy to pay you in dollars, but you will most likely get change in lira and at a rate that is not very favorable for you, so it is still worth exchanging some cash in advance.
You can also pay with checks and credit cards, but they are not always accepted everywhere. A tax is often charged for using credit cards (sometimes there is no warning about this, 5-7% of the cashed amount is simply debited from the account).