Warsaw is the capital city of Poland and its largest city. It is located on the Vistula River roughly 370 kilometers (230 mi) from both the Baltic Sea coast and the Carpathian Mountains. Its population as of 2007 was estimated at 1,704,717, with a metropolitan area of approximately 3,350,000. The city area is 516.9 square kilometers (199.6 sq mi), with an agglomeration of 6,100.43 square kilometers (2,355.4 sq mi) (Warsaw Metro Area — Obszar Metropolitalny Warszawy). Warsaw is the 8th largest city in the European Union.

Warsaw gave its name to the Warsaw Pact, Warsaw Convention, Treaty of Warsaw and the Warsaw Uprising.

An older spelling of Warsaw in Polish is Warszewa or Warszowa, meaning "owned by Warsz." Folk etymology attributes the city name to a fisherman Wars and his wife Sawa. Actually, Warsz was a nobleman (12th/13th century) who owned a village located at the site of today's Mariensztat neighbourhood.

The official city name in full is The Capital City of Warsaw (Polish: Miasto Stoleczne Warszawa). Warsaw has been known in Latin as Varsovia. A native or resident of Warsaw is called Varsovian.

The first fortified settlements on the site of today's Warsaw were Bródno (9th/10th century) and Jazdów (12th/13th century). After Jazdów was raided, a new similar settlement was established on the site of a small fishing village called Warszowa. This settlement Warszowa (at present Warsaw) a Plock prince established (about 1300), Boleslaw II Mazovian (from 1294 prince of entire Masovia). In the beginning of the 14th century it became one of the seats of the Dukes of Masovia, becoming the capital of Masovia in 1413. Upon the extinction of the local ducal line, the duchy was reincorporated into the Polish Crown in 1526. In 1529 Warsaw for the first time became the seat of the General Sejm, permanent since 1569. In 1573 Warsaw gave its name to the Warsaw Confederation, formally establishing religious freedom in the Polish-Lithuanian Commonwealth.

Due to its central location between the Polish-Lithuanian Commonwealth's capitals of Kraków and Vilnius, Warsaw became the capital of the Commonwealth and at the same time of the Polish Crown in 1596, when King Sigismund III Vasa moved the court from Kraków. Warsaw remained the capital of the Polish-Lithuanian Commonwealth until 1795, when it was annexed by the Kingdom of Prussia to become the capital of the province of South Prussia. Liberated by Napoleon's army in 1807, Warsaw was made the capital of the newly created Duchy of Warsaw. Following the Congress of Vienna of 1815, Warsaw became the centre of the Congress Poland, a constitutional monarchy under a personal union with Imperial Russia. The Royal University of Warsaw was established in 1816.

Following the repeated violations of the Polish constitution by the Russians, the 1830 November Uprising broke out. However, the Polish-Russian war of 1831 ended in the uprising's defeat and in the curtailment of the Kingdom's autonomy. On 27 February 1861 a Warsaw crowd protesting the Russian rule over Poland was fired upon by the Russian troops. Five people were killed. The Underground Polish National Government resided in Warsaw during January Uprising in 1863–4.

Warsaw flourished in the late nineteenth century under Mayor Sokrates Starynkiewicz (1875–92), a Russian-born general appointed by Tsar Alexander III. Under Starynkiewicz Warsaw saw its first water and sewer systems designed and built by the English engineer William Lindley and his son, William Heerlein Lindley, as well as the expansion and modernization of trams, street lighting and gas works.

Warsaw became the capital of the newly independent Poland in 1918. In the course of the Polish-Bolshevik War of 1920, the huge Battle of Warsaw was fought on the Eastern outskirts of the city in which the capital was successfully defended and the Red Army defeated. Poland stopped on itself the full brunt of the Red Army and defeated an idea of the "export of the revolution."

During the Second World War central Poland, including Warsaw, came under the rule of the General Government, a Nazi colonial administration. All higher education institutions were immediately closed and Warsaw's entire Jewish population — several hundred thousand, some 30% of the city — herded into the Warsaw Ghetto. When the order came to annihilate the Ghetto as part of Hitler's "final solution" on April 19, 1943, Jewish fighters launched the Warsaw Ghetto Uprising. Despite being heavily outgunned and outnumbered, the Ghetto held out for almost a month. When the fighting ended, almost all survivors were massacred, only few managed to escape or hide.

By July 1944 the Red Army was deep into Polish territory pursuing the Germans toward Warsaw. Knowing that Stalin was hostile to the idea of an independent Poland, the Polish government-in-exile based in London gave orders to the underground Home Army (AK) to try to seize the control of Warsaw from the Nazis just before the Red Army's arrival. Thus, on 1 August 1944, as the Soviet army was nearing the city very fast, the Home Army and the civilian population started the Warsaw Uprising. The armed struggle, planned to last 48 hours, went on for 63 days, and eventually the Home Army fighters were forced to capitulate. They were transported to the POW camps in Germany, while the entire civilian population was expelled. Hitler, ignoring the agreed terms of the capitulation, ordered the entire city to be razed to the ground, and the library and museum collections taken to Germany or burned. Monuments and government buildings were blown up by special German troops known as Verbrennungs und Vernichtungskommando (burning and destruction detachments). About 85% of the city had been destroyed, including the historic Old Town and the Royal Castle. After the war, large prefabricated housing projects were erected in Warsaw to address the housing shortage. The city resumed its role as the capital of Poland and the country's centre of political and economic life. Many of the historic streets, buildings, and churches were restored to their original form. In 1980 Warsaw's historic Old Town was inscribed onto UNESCO's World Heritage list.

In 1995 the Warsaw Metro opened, and with the entry of Poland into the European Union in 2004, Warsaw is currently experiencing the biggest economic boom of its history. The opening match of the UEFA Euro 2012 is scheduled to take place in Warsaw.