While planning your trip to Turkey do not forget to check your passport if it is valid for at least 180 days. Depending on your nationality, most probably your stay as a tourist is limited up to 3 months (for one entrance).For tourist visas for many countries, there is no need to apply in advance or to fill in any forms. However, please check the Ministry of Foreign Affairs website for updated information and information on which passport holders may require a visa before leaving their country. You may also check with the Turkish Embassy in your country for the latest visa updates. The visa for UK passport holders currently costs £10 and must be paid for with a Sterling note. The visa fee for USA and Australian passport holders is $20/€15. Canadian passport holders need to pay $60/€45. The visa fee for New Zealand passport holders is gratis. The visa for some EU state-passport holders currently costs € 10 and must be paid for with a Euro note.Visas are multiple entries and are valid for three months. 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 a business in Turkey.
Also you can apply online visa e-Visa – Republic of Turkey Electronic Visa Application System