Visitors from certain countries require a valid visa for entry to Turkey. It is your responsibility to check the visa requirement status for your nationality and complete the proper visa procedures.
Please visit
http://www.mfa.gov.tr/visa-information-for-foreigners.en.mfa for visa requirements.
Online e visa service is available for the citizens of many countries.
Please visit
https://www.evisa.gov.tr/en/ for more information.