An attack on a nightclub in Istanbul, Turkey, during New Year's celebrations, kills 39 people and injures 79 others.

The Istanbul nightclub shooting was a mass shooting incident on 1 January 2017 around 01:15 local time, in which a terrorist shot and killed 39 people and wounded 79 others at the Reina nightclub in the Ortaköy neighbourhood of Istanbul, Turkey, where hundreds had been celebrating New Year's Day. Uzbekistan-born Abdulkadir Masharipov was arrested in Istanbul on 17 January 2017. Islamic State claimed credit for his actions. The first hearing in the trial of Masharipov and 51 accused accomplices was held on 11 December 2017, and the next hearing was held on 26 March 2018.

Istanbul is the largest city in Turkey, constituting the country's economic, cultural, and historical heart. With a population over 15 million, it is home to 18% of the population of Turkey. Istanbul is among the largest cities in Europe and in the world by population. It is a city on two continents; about two-thirds of its population live in Europe and the rest in Asia. Istanbul straddles the Bosphorus—one of the world's busiest waterways—in northwestern Turkey, between the Sea of Marmara and the Black Sea. Its area of 5,461 square kilometers (2,109 sq mi) is coterminous with Istanbul Province.

Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia, Armenia, Azerbaijan, and Iran to the east; Iraq, Syria, and the Mediterranean Sea to the south; and the Aegean Sea, Greece, and Bulgaria to the west. Turkey is home to over 85 million people; most are ethnic Turks, while ethnic Kurds are the largest ethnic minority. Officially a secular state, Turkey has a Muslim-majority population. Ankara is Turkey's capital and second-largest city. Istanbul is its largest city and economic center. Other major cities include İzmir, Bursa, and Antalya.