Turkey is the only secular country in the Islamic world. Secularism is enshrined in the constitution that religion has no place whatsoever in governing of the country. Like other European countries, the weekly holiday is Sunday - not Friday as many are mistaken- and the Gregorian calendar is used in Turkey. The constitution secures the freedom of belief and worshiping. During the time of the Ottoman Empire, people of many different faiths lived together in peace, and since then this diversity has been preserved. Today there are 236 churches and 34 synagogues open for worship in Turkey
Tourists visiting Turkey are unlikely to see much evidence that they are in a Muslim country, except for the call to prayer, which can be heard 5 times a day. People wear contemporary dresses like any western country, and especially in big cities and popular holiday destinations, one can easily spot many who are closely observing fashion of Paris, London and Milan. There is no difference in the way people dress, especially in large cities in Turkey to the rest of Europe. It is only in smaller villages, more remote areas and the east of the country that dress codes are more local. It is quite common for village women to wear headscarves but this is generally out of practical and cultural rather than religious considerations.
The only time you need to be mindful about dress codes is when visiting a mosque. Everyone should wear clothing that covers his or her legs, so no shorts, much like in any temple. Women should also make sure that their shoulders and head are covered. Shoes should be removed before entering a mosque. There is usually a rack or storage area where they can be left or you can carry them with you in a bag. Mosques are usually closed to visitors during prayer times.
There are two major Islamic Festivals, which are celebrated in Turkey. The dates of both change each year, according to lunar calendar. Eid (Ramazan or Şeker Bayramı) falls at the end of period of fasting. Greater Eid, the Feast of Sacrifice (Kurban Bayramı) falls almost two months after Eid, when wealthy believers usually sacrifice a sheep or a cow and it is distributed to the needy including friends, family and neighbours. Government offices and some other institutions are closed during these periods but life in resorts continues much as usual, and many Turks also head to the holiday destinations.