The Russian Empire (also known as Russia) is an empire that exists from 1721 until it is overthrown by the short-lived February Revolution in 1917.

One of the largest empires in world history, stretching over three continents, the Russian Empire is surpassed in landmass only by the British and Mongol empires.

The rise of the Russian Empire happens in association with the decline of neighboring rival powers: the Swedish Empire, the Polish–Lithuanian Commonwealth, Persia and the Ottoman Empire

It plays a major role in 1812–1814 in defeating Napoleon's ambitions to control Europe and expanded to the west and south.

The House of Romanov rules the Russian Empire from 1721 until 1762, and its German-descended cadet branch, the House of Holstein-Gottorp-Romanov, ruled from 1762.

At the beginning of the nineteenth century, the Russian Empire extends from the Arctic Ocean in the north to the Black Sea in the south, from the Baltic Sea on the west to the Pacific Ocean, and (until 1867) into Alaska in North America on the east.

With 125.6 million subjects registered by the 1897 census, it has the third-largest population in the world at the time, after Qing China and India

Like all empires, it includes a large disparity in terms of economics, ethnicity, and religion.

There are numerous dissident elements, who launch numerous rebellions and assassination attempts; they are closely watched by the secret police, with thousands exiled to Siberia.

Economically, the empire has a predominately agricultural base, with low productivity on large estates worked by serfs (until they were freed in 1861).

The economy slowly industrializes with the help of foreign investments in railways and factories.

The land had been ruled by a nobility (the boyars) from the tenth through the seventeenth centuries, and subsequently by an emperor.

Tsar Ivan III (1462–1505) had laid the groundwork for the empire that later emerges.

He had tripled the territory of his state, ended the dominance of the Golden Horde, renovated the Moscow Kremlin, and laid the foundations of the Russian state.

Tsar Peter the Great (1682–1725) fights numerous wars and expands an already huge empire into a major European power.

He moves the capital from Moscow to the new model city of St. Petersburg, and leads a cultural revolution that replaces some of the traditionalist and medieval social and political mores with a modern, scientific, Europe-oriented, and rationalist system.

Catherine the Great (reigned 1762–1796) presides over a Golden age.

She expands the state by conquest, colonization and diplomacy, continuing Peter the Great's policy of modernization along West European lines.

Tsar Alexander II (1855–1881) promotes numerous reforms, most dramatically the emancipation of all twenty-three million serfs in 1861.

His policy in Eastern Europe involves protecting the Orthodox Christians under the rule of the Ottoman Empire.

That connection by 1914 led to Russia's entry into the First World War on the side of France, Britain, and Serbia, against the German, Austrian and Ottoman empires.

The Russian Empire functions as an absolute monarchy until the Revolution of 1905, then becomes a de jure constitutional monarchy.

The empire collapses during the February Revolution of 1917, largely as a result of massive failures in its participation in the First World War.