Russia, or the Russian Federation, is a country in Eastern Europe and North Asia. It is the largest country in the world, spanning eleven time zones and sharing land borders with fourteen countries. With over 140 million people, Russia is the most populous country in Europe and the ninth-most populous in the world. It is a highly urbanised country, with sixteen of its urban areas having more than 1 million inhabitants. Moscow, the most populous metropolitan area in Europe, is the capital and largest city of Russia; Saint Petersburg is its second-largest city and cultural centre.

Human settlement on the territory of modern Russia dates back to the Lower Paleolithic. The East Slavs emerged as a recognised group in Europe between the 3rd and 8th centuries AD. The first East Slavic state, Kievan Rus', arose in the 9th century, and in 988, it adopted Orthodox Christianity from the Byzantine Empire. Kievan Rus' ultimately disintegrated; the Grand Duchy of Moscow led the unification of Russian lands, leading to the proclamation of the Tsardom of Russia in 1547. By the early 18th century, Russia had vastly expanded through conquest, annexation, and the efforts of Russian explorers, developing into the Russian Empire, which remains the third-largest empire in history. However, with the Russian Revolution in 1917, Russia's monarchic rule was abolished and eventually replaced by the Russian SFSR—the world's first constitutionally socialist state. Following the Russian Civil War, the Russian SFSR established the Soviet Union with three other Soviet republics, within which it was the largest and principal constituent. The Soviet Union underwent rapid industrialisation in the 1930s, amidst the deaths of millions under Joseph Stalin's rule, and later played a decisive role for the Allies in World War II by leading large-scale efforts on the Eastern Front. With the onset of the Cold War, it competed with the United States for ideological dominance and international influence. The Soviet era of the 20th century saw some of the most significant Russian technological achievements, including the first human-made satellite and the first human expedition into outer space.

In 1991, the Russian SFSR emerged from the dissolution of the Soviet Union as the Russian Federation. Following the 1993 Russian constitutional crisis, the Soviet system of government was abolished and a new constitution was adopted, which established a federal semi-presidential system. Since the turn of the century, Russia's political system has been dominated by Vladimir Putin, under whom the country has experienced democratic backsliding and become an authoritarian dictatorship. Russia has been militarily involved in a number of conflicts in former Soviet states and other countries, including its war with Georgia in 2008 and its war with Ukraine since 2014. The latter has involved the internationally unrecognised annexations of Ukrainian territory, including Crimea in 2014 and four other regions in 2022, during an ongoing invasion.

Russia is generally considered a great power and is a regional power, possessing the largest stockpile of nuclear weapons and having the third-highest military expenditure in the world. Its advanced economy ranks among the largest in the world, relying on its vast mineral and energy resources, mainly oil and natural gas production. Russia ranks very low in international measurements of democracy, human rights and freedom of the press, and also has high levels of perceived corruption. It is a permanent member of the United Nations Security Council as well as a member state of the SCO and several other intergovernmental organisations. Russia is home to 32 UNESCO World Heritage Sites.

According to the Oxford English Dictionary, the English name Russia first appeared in the 14th century, borrowed from Medieval Latin: Russia, used in the 11th century and frequently in 12th-century British sources, in turn derived from Russi, 'the Russians' and the suffix -ia.

There are several words in Russian which translate to "Russians" in English. The noun and adjective русский, russkiy refers to ethnic Russians. The adjective российский, rossiiskiy denotes Russian citizens regardless of ethnicity. The same applies to the more recently coined noun россиянин, rossiianyn, in the sense of citizen of the Russian state.

The oldest endonyms used were Rus' (Русь) and the "Russian land" (Русская земля, Russkaya zemlya). According to the Primary Chronicle, the word Rus' is derived from the Rus' people, who were a Swedish tribe, and from where the three original members of the Rurikid dynasty came from. The Finnish word for Swedes, ruotsi, has the same origin. In modern historiography, the early medieval East Slavic state is usually referred to as Kievan Rus', named after its capital city. Another Medieval Latin name for Rus' was Ruthenia.

In Russian, the current name of the country, Россия (Rossiya), comes from the Byzantine Greek name Ρωσία (Rosía). The name Росия (Rosiya) was first attested in 1387. The name Rossiya appeared in Russian sources in the 15th century and began to replace the vernacular Rus' during the rise of Moscow as the centre of a unified Russian state. However, until the end of the 17th century, the country was more often referred to by its inhabitants as Rus', the "Russian land" (Russkaya zemlya), or the "Muscovite state" (Moskovskoye gosudarstvo), among other variations.