Spain becomes one of history's first global colonial empires in the early modern period, leaving a vast cultural and linguistic legacy that includes over five hundred million Spanish speakers, making Spanish the world's second most spoken first language, after Mandarin Chinese.

Habsburg Spain refers to the history of Spain over the sixteenth and seventeenth centuries (1516–1700), when it is ruled by kings from the House of Habsburg (also associated with its role in the history of Central Europe).

The Habsburg rulers (chiefly Charles I and Philip II) reach the zenith of their influence and power.

They control  territory that includes the Americas, the East Indies, the Low Countries and territories now in France and Germany in Europe, the Portuguese Empire from 1580 to 1640, and various other territories such as small enclaves like Ceuta and Oran in North Africa.

This period of Spanish history has also been referred to as the "Age of Expansion".

Under the Habsburgs, Spain dominates Europe politically and militarily for much of the sixteenth and seventeenth centuries but experiences a gradual decline of influence in the second half of the seventeenth century under the later Habsburg kings.

"Spain" or "the Spains" in this period covers the entire peninsula, politically a confederacy comprising several, nominally independent kingdoms in personal union: Aragon, Castile, León, Navarre and, from 1580, Portugal.

In some cases, these individual kingdoms themselves are confederations, most notably, the Crown of Aragon (Principality of Catalonia, Kingdom of Aragon, Kingdom of Valencia, and the Kingdom of Majorca).

The marriage of Isabella I of Castile and Ferdinand II of Aragon in 1469 had enabled the union two of the greatest of these kingdoms, Castile and Aragon, which led to their largely successful campaign against the Moors, peaking at the conquest of Granada in 1492.

Isabella and Ferdinand had been bestowed the title of Most Catholic Monarchs by Pope Alexander VI in 1496, and the term Monarchia Catholica (Catholic Monarchy, Modern Spanish: Monarquía Católica) remains in use for the monarchy under the Spanish Habsburgs.

The Habsburg period is formative of the notion of "Spain" in the sense that is institutionalized in the eighteenth century.

From the seventeenth century, during and after the end of the Iberian Union, the Habsburg monarchy in Spain is also known as "Spanish Monarchy" or "Monarchy of Spain", along with the common form Kingdom of Spain.

Spain as a unified state comes into being de jure only after the death in 1700 of Charles II and with it the extinction of the Spanish Habsburg dynasty, and the ascension of Philip V and the inauguration of the Bourbon dynasty and its central reforms, comparable to those in France.