Catalonia is an autonomous community of Spain, designated as a nationality by its Statute of Autonomy. Most of its territory (except the Val d'Aran) is situated on the northeast of the Iberian Peninsula, to the south of the Pyrenees mountain range. Catalonia is administratively divided into four provinces or eight vegueries (regions), which are in turn divided into 43 comarques. The capital and largest city, Barcelona, is the second-most populous municipality in Spain and the fifth-most populous urban area in the European Union.

Modern-day Catalonia comprises most of the medieval and early modern Principality of Catalonia, with the remainder of the northern area now part of France's Pyrénées-Orientales. It is bordered by France (Occitanie) and Andorra to the north, the Mediterranean Sea to the east, and the Spanish autonomous communities of Aragon to the west and Valencia to the south. In addition to its approximately 580 km of coastline, Catalonia also has major high landforms such as the Pyrenees and the Pre-Pyrenees, the Transversal Range (Serralada Transversal) or the Central Depression. The official languages are Catalan, Spanish, and the Aranese dialect of Occitan.

In 1137, the County of Barcelona and the Kingdom of Aragon formed a dynastic union, resulting in a composite monarchy, the Crown of Aragon. Within the Crown, Barcelona and the other Catalan counties merged in to a state, the Principality of Catalonia, with its distinct institutional system, such as Courts, Generalitat, and constitutions, being the base and promoter for the Crown's Mediterranean trade and expansionism. Catalan literature flourished. In 1516, Charles V became monarch of the crowns of Aragon and Castile, retaining both their previous distinct institutions and legislation. Growing tensions led to the revolt of the Principality of Catalonia (1640–1652), briefly as a republic under French protection. By the Treaty of the Pyrenees (1659), the northern parts of Catalonia were ceded to France. During the War of the Spanish Succession (1701–1714), the states of the Crown of Aragon sided against the Bourbon Philip V, but following Catalan capitulation (11 September 1714) he imposed a unifying administration across Spain via the Nueva Planta decrees which suppressed Catalonia's institutions and legal system, thus ending its separate status. Catalan as a language of government and literature was eclipsed by Spanish.

In the 19th century, Napoleonic and Carlist Wars affected Catalonia, however, it experienced industrialisation, as well as a cultural renaissance coupled with incipient nationalism and several workers' movements. The Second Spanish Republic (1931–1939) granted self-governance to Catalonia, restoring the Generalitat as its government. After the Spanish Civil War (1936–1939), the Francoist dictatorship enacted repressive measures, abolishing self-government and banning again the official use of the Catalan language. After a harsh autarky, from the late 1950s Catalonia saw rapid economic growth, drawing many workers from across Spain and making it a major industrial and touristic hub. During the Spanish transition to democracy (1975–1982), the Generalitat and Catalonia's self-government were reestablished, remaining one of the most economically dynamic communities in Spain.

In the 2010s, there was growing support for Catalan independence. On 27 October 2017, the Catalan Parliament unilaterally declared independence following a referendum that was deemed unconstitutional. The Spanish State enforced direct rule by removing the Catalan government and calling a snap regional election. The Spanish Supreme Court imprisoned seven former Catalan ministers on charges of rebellion and misuse of public funds, while several others—including then-President Carles Puigdemont—fled to other European countries. Those in prison were pardoned in 2021.

The name "Catalonia" (Medieval Latin: Cathalaunia), spelled Cathalonia, began to be used for the homeland of the Catalans (Cathalanenses) in the late 11th century and was probably used before as a territorial reference to the group of counties that comprised part of the March of Gothia and the March of Hispania under the control of the Count of Barcelona and his relatives. The origin of the name Catalunya is subject to diverse interpretations because of a lack of evidence.

One theory suggests that Catalunya derives from the name Gothia (or Gauthia) Launia ("Land of the Goths"), since the origins of the Catalan counts, lords and people were found in the March of Gothia, known as Gothia, whence Gothland > Gothlandia > Gothalania > Cathalaunia > Catalonia theoretically derived. During the Middle Ages, Byzantine chroniclers claimed that Catalania derives from the local medley of Goths with Alans, initially constituting a Goth-Alania.

Other theories suggest: