Please note that your passport must have at least three months’ validity remaining, or you may not be admitted into Turkey. You are kindly advised to have a passport valid for at least 6 months as from the date of your arrival in Turkey.
Depending on your nationality, most probably you do not need visa to Turkey and your stay as a tourist is limited up to 3 months (for one entrance). In case you need visa (check HERE), for tourist visas, you are kindly advised to enter the Electronic Visa (e-Visa) Application System and easily obtain your e-Visa online (www.evisa.gov.tr) in approximately three minutes. If you are flying to Turkey, you can also buy your visa at the Turkish airport upon arrival. You will see the visa desk, situated just in front of the passport control. You must buy your visa, which will be stamped on your passport by the official, before you join the queue for passport control. Fees for e-Visas obtained via the e-Visa website (www.evisa.gov.tr) are lower than the fees for visas obtained upon arrival to Turkish airports. Information regarding visa fees can be found on the website of the Ministry of Foreign Affairs.(https://www.mfa.gov.tr/data/KONSOLOSLUK/vize-harc-miktarlari-en.pdf). Each passport-holder, including infants, must purchase a visa. With tourist visas you will not have the right to take up paid or unpaid employment or to reside, or to study (including student exchange program) or to establish yourself in business in Turkey.
For more detailed information please see the official website of Ministry of Foreign Affairs of Turkey. https://www.mfa.gov.tr/visa-information-for-foreigners.en.mfa