At the time of research, nationals of countries including Denmark, Finland, France, Germany, Greece, Israel, Italy, Japan, New Zealand, Sweden and Switzerland don't need a visa to visit Turkey for up to 90 days.
Russians could enter without a visa for up to 60 days.
Nationals of countries including Australia, Austria, Belgium, Canada, India, Ireland, Mexico, the Netherlands, Norway, Portugal, Spain, Taiwan, the UK and USA need a visa, which should be purchased online at www.evisa.gov.tr before travelling.
Most nationalities, including the above, are given a 60- or 90-day multiple-entry visa.
You must enter details of your passport and date of arrival in Turkey, click on the link in the verification email and pay with a Mastercard or Visa credit or debit card.
Having completed this process, the e-visa can be downloaded in Adobe PDF format; a link is also emailed so it can be printed out later.
It is recommended that you print out the e-visa to show on arrival in Turkey; keep it while in the country.
It is recommended that applications are made at least 48 hours before departure.
Many Western nationals can obtain a visa on arrival in Turkey, but this is not recommended as travellers have reported extra charges and bad experiences with the customs officials. Cash cannot be used.
Visa fees cost US$15 to US$80, depending on nationality.
In some cases, the 90-day visa stipulates 'per period 180 days'. This means you can spend three months in Turkey within a six-month period; when you leave after three months, you can't re-enter for three months.
Check the Ministry of Foreign Affairs (www.mfa.gov.tr, www.evisa.gov.tr) for more information.