Austria, officially the Republic of Austria, is a country in the southern part of Central Europe. It is a federation of nine states, one of which is the capital Vienna, the largest city and state by population. The country is bordered by Germany to the northwest, the Czech Republic to the north, Slovakia to the northeast, Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west. It occupies a landlocked area of 83,879 km2 (32,386 sq mi) and has a population of 9 million people.Austria emerged from the remnants of the Eastern and Hungarian March at the end of the first millennium. Originally a margraviate of Bavaria, it later developed into a duchy of the Holy Roman Empire in 1156, and then an archduchy in 1453. As of the 16th century, Vienna began serving as the administrative imperial capital and Austria thus became the heartland of the House of Habsburg. Following the Empire's dissolution in 1806, Austria established its own empire, which became a great power and the dominant member of the German Confederation. The Austrian Empire's defeat in the Austro-Prussian War of 1866 led to the end of the Confederation and paved the way for the establishment of Austria-Hungary a year later.

Following the assassination of Archduke Franz Ferdinand in 1914, Emperor Franz Joseph declared war on Serbia, which ultimately escalated into World War I. The Empire's defeat and subsequent collapse led to the proclamation of the Republic of German-Austria in 1918 and later the First Austrian Republic in 1919. During the interwar period, anti-parliamentarian sentiments culminated in the formation of an Austrofascist dictatorship under Engelbert Dollfuss in 1934. A year before the outbreak of World War II, Austria was annexed into Nazi Germany by Adolf Hitler, and it became a sub-national division. Following its liberation in 1945 and an extended period of Allied occupation, the country regained its sovereignty and declared its perpetual neutrality in 1955.

Austria is a parliamentary representative democracy with a popularly elected president as head of state and a chancellor as head of government and chief executive. Major urban areas include Vienna, Graz, Linz, Salzburg and Innsbruck. Austria is consistently listed as one of the richest countries in the world by GDP per capita, one of the countries with the highest standard of living, and was ranked 18th in the world for its Human Development Index in 2020.

Austria has been a member of the United Nations since 1955 and of the European Union since 1995. It plays host to the OSCE and OPEC and is a founding member of the OECD and Interpol. It also signed the Schengen Agreement in 1995, and adopted the euro currency in 1999.

The Anschluss (German: [ˈʔanʃlʊs] (listen), or Anschluß, "joining"), also known as the Anschluss Österreichs (pronunciation , English: Annexation of Austria), was the annexation of Austria into Nazi Germany on 12 March 1938.

The idea of an Anschluss (a united Austria and Germany that would form a "Greater Germany") began after the unification of Germany excluded Austria and the German Austrians from the Prussian-dominated German Empire in 1871. Following the end of World War I with the fall of the Austro-Hungarian Empire, in 1918, the newly formed Republic of German-Austria attempted to form a union with Germany, but the Treaty of Saint Germain (10 September 1919) and the Treaty of Versailles (28 June 1919) forbade both the union and the continued use of the name "German-Austria" (Deutschösterreich); and stripped Austria of some of its territories, such as the Sudetenland.

Prior to the Anschluss, there had been strong support in both Austria and Germany for unification of the two countries. In the immediate aftermath of the dissolution of the Habsburg Monarchy—with Austria left as a broken remnant, deprived of most of the territories it ruled for centuries and undergoing a severe economic crisis—the idea of unity with Germany seemed attractive also to many citizens of the political left and center.

But after 1933, when the Austrian-born Adolf Hitler rose to power in Germany, desire for unification could be identified with the Nazis, for whom it was an integral part of the Nazi "Heim ins Reich" concept, which sought to incorporate as many Volksdeutsche (ethnic Germans outside Germany) as possible into a "Greater Germany". Nazi Germany's agents cultivated pro-unification tendencies in Austria, and sought to undermine the Austrian government, which was controlled by the Austrofascist Fatherland Front. During an attempted coup in 1934, Austrian chancellor Engelbert Dollfuss was assassinated by Austrian Nazis. The defeat of the coup prompted many leading Austrian Nazis to go into exile in Germany, where they continued their efforts for unification of the two countries.

In early 1938, under increasing pressure from pro-unification activists, Austrian chancellor Kurt Schuschnigg announced that there would be a referendum on a possible union with Germany versus maintaining Austria's sovereignty to be held on 13 March. Portraying this as defying the popular will in Austria and Germany, Hitler threatened an invasion and secretly pressured Schuschnigg to resign. A day before the planned referendum, on 12 March, the German Wehrmacht crossed the border into Austria, unopposed by the Austrian military; to be greeted with great enthusiasm. A plebiscite (Result: 99.71%) held on 10 April officially ratified Austria's annexation by the Reich.