Kyiv, also Kiev, is the capital and most populous city of Ukraine. Located in the north-central part of the country, it straddles both sides of the Dnieper River. As of 1 January 2022, its population was 2,952,301, making Kyiv the seventh-most populous city in Europe. Kyiv is an important industrial, scientific, educational, and cultural center. It is home to many high-tech industries, higher education institutions, and historical landmarks. The city has an extensive system of public transport and infrastructure, including the Kyiv Metro.

The city's name is said to derive from the name of Kyi, one of its four legendary founders. During its history, Kyiv, one of the oldest cities in Eastern Europe, passed through several stages of prominence and obscurity. The city probably existed as a commercial center as early as the 5th century. A Slavic settlement on the great trade route between Scandinavia and Constantinople, Kyiv was a tributary of the Khazars, until its capture by the Varangians (Vikings) in the mid-9th century. Under Varangian rule, the city became a capital of Kievan Rus', the first East Slavic state. Completely destroyed during the Mongol invasions in 1240, the city lost most of its influence for the centuries to come. Coming under Lithuania, then Poland and then Russia, the city would grow from a frontier market into an important centre of Orthodox learning in the sixteenth century, and later of industry, commerce, and administration by the nineteenth.

The city prospered again during the Russian Empire's Industrial Revolution in the late 19th century. In 1918, when the Ukrainian People's Republic declared independence from the Russian Republic after the October Revolution there, Kyiv became the republic's capital. From the end of the Ukrainian-Soviet and Polish-Soviet wars in 1921, Kyiv was part of the Ukrainian SSR, of which it became the capital in 1934. The city suffered significant destruction during World War II but quickly recovered in the postwar years, remaining the Soviet Union's third-largest city.

Following the collapse of the Soviet Union and Ukrainian independence in 1991, Kyiv remained Ukraine's capital and experienced a steady influx of ethnic Ukrainian migrants from other regions of the country. During the country's transformation to a market economy and electoral democracy, Kyiv has continued to be Ukraine's largest and wealthiest city. Its armament-dependent industrial output fell after the Soviet collapse, adversely affecting science and technology, but new sectors of the economy such as services and finance facilitated Kyiv's growth in salaries and investment, as well as providing continuous funding for the development of housing and urban infrastructure. Kyiv has emerged as the most pro-Western region of Ukraine; parties advocating tighter integration with the European Union dominate during elections in Ukraine.

The traditional etymology, stemming from the Primary Chronicle, is that the name is a derivation of Kyi (Ukrainian: Кий, Russian: Кий, rom.: Ky or Kiy), the legendary eponymous founder of the city. According to Oleg Trubachyov's etymological dictionary from the Old East Slavic name *Kyjevŭ gordŭ (literally, "Kyi's castle", "Kyi's gord"), from Proto-Slavic *kyjevъ, This etymology has been questioned, for instance by Mykhailo Hrushevsky, who called it an "etymological myth", and meant that the names of the legendary founders are in turn based on place names. According to the Ukrainian-Canadian linguist Jaroslav Rudnyckyj, the name can be connected to the Proto-Slavic root *kyjь, but should be interpreted as meaning 'stick, pole' as in its modern Ukrainian equivalent Кий. The name should in that case be interpreted as 'palisaded settlement'.

Kyiv is the official romanized Ukrainian name for the city, and it is used for legislative and official acts. Kiev is the traditional English name for the city, but because of its historical derivation from the Russian name, Kiev lost favor with many Western media outlets after the outbreak of the Russo-Ukrainian War in 2014 in conjunction with the KyivNotKiev campaign launched by Ukraine to change the way that international media were spelling the city's name.

The first known humans in the region of Kyiv lived there in the late Paleolithic period (Stone Age). The population around Kyiv during the Bronze Age formed part of the so-called Trypillian culture, as evidenced by artifacts from that culture found in the area. During the early Iron Age certain tribes settled around Kyiv that practiced land cultivation, husbandry and trading with the Scythians and ancient states of the northern Black Sea coast. Findings of Roman coins of the 2nd to the 4th centuries suggest trade relations with the eastern provinces of the Roman Empire.

Scholars continue to debate when the city was founded: The traditional founding date is 482 CE, so the city celebrated its 1,500th anniversary in 1982. Archaeological data indicates a founding in the sixth or seventh centuries, with some researchers dating the founding as late as the late 9th century.