The Spanish Empire (Spanish: Imperio Español) comprised territories and colonies administered by Spain in Europe, the Americas, Africa, Asia and Oceania. It originated during the Age of Exploration and was one of the first global empires. At the time of Habsburgs, Spain reached the peak of its political and economic power when it became the foremost global power. Its establishment in the 15th century ushered in the modern global era and five centuries of European dominance of global affairs. Spain's territorial reach beyond Europe spanned six centuries, from the first voyages to the Americas in 1492 until the independence of its last African colonies in the 1970s.

After the War of the Castilian Succession (1475–1479), Spain had emerged with a personally unified monarchy, with the marriage of the Catholic Monarchs or los Reyes Catolicos between the Queen of Castile and the King of Aragon: the internal and foreign policy was coordinated although the rule was separate. In 1492, the Spanish monarchs completed the Reconquista with the incorporation of Granada to the Kingdom of Castile. That same year Christopher Columbus commanded the first Spanish exploratory voyage west across the Atlantic Ocean, leading to the Discovery of America and Europe's eventual colonial engagement in the New World. The Americas thereby became the focus of Spanish exploration and colonization.

Guns, Germs, and Steel: The Fates of Human Societies is a 1997 book by Jared Diamond, professor of geography and physiology at the University of California, Los Angeles (UCLA). In 1998, it won the Pulitzer Prize for general non-fiction and the Aventis Prize for Best Science Book. A documentary based on the book, and produced by the National Geographic Society, was broadcast on PBS in July 2005.

It was also published under the title Guns, Germs and Steel: A short history of everybody for the last 13,000 years. The book attempts to explain why Eurasian civilizations (in which he includes North Africa) have survived and conquered others, while refuting the assumption that Eurasian hegemony is due to any form of Eurasian intellectual, moral or inherent genetic superiority. Diamond argues that the gaps in power and technology between human societies originate in environmental differences, which are amplified by various positive feedback loops. When cultural or genetic differences have favored Eurasians (for example, written language or the development among Eurasians of resistance to endemic diseases), he asserts that these advantages occurred because of the influence of geography on societies and cultures, and were not inherent in the Eurasian genomes.

A Spanish American is a citizen or resident of the United States whose ancestors originate from the southwestern European nation of Spain. Spanish Americans are the earliest European American group, with a continuous presence since 1565.

In colonial times there were a number of Spanish populations in the present–day U.S. with governments answerable to Madrid. The first settlement was in St. Augustine, Florida, followed by others in New Mexico, California, Arizona, Texas, and Louisiana. In 1598, San Juan de los Caballeros was established, near present day Santa Fe, New Mexico, by Juan de Oñate and about 1,000 other Spaniards. After the establishment of the American colonies, an additional 250,000 immigrants arrived either directly from Spain, the Canary Islands or, after a relatively short sojourn, from present-day central Mexico. The Canary Islanders settled San Antonio de Bejar, San Antonio, Texas, in 1731.^{[citation needed]} Most of the Spanish settlers in present-day Texas, California, New Mexico, Colorado, and Arizona were of ethnically-mixed ancestry, or mestizo. Most self-identified Spanish-Americans in the Southwest differentiate themselves nominally from the population of Mexican-Americans who came after the Mexican Revolution.

Christopher Columbus (before 31 October 1451 – 20 May 1506) was an explorer, colonizer, and navigator, born in the Republic of Genoa, in what is today northwestern Italy. Under the auspices of the Catholic Monarchs of Spain, he completed four voyages across the Atlantic Ocean that led to general European awareness of the American continents. Those voyages, and his efforts to establish permanent settlements in the island of Hispaniola, initiated the process of Spanish colonization, which foreshadowed the general European colonization of what became known as the "New World".

In the context of emerging western imperialism and economic competition between European kingdoms seeking wealth through the establishment of trade routes and colonies, Columbus's speculative proposal to reach the East Indies by sailing westward received the support of the Spanish crown, which saw in it a promise, however remote, of gaining the upper hand over rival powers in the contest for the lucrative spice trade with Asia. During his first voyage in 1492, instead of reaching Japan as he had intended, Columbus landed in the Bahamas archipelago, at a locale he named San Salvador. Over the course of three more voyages, Columbus visited the Greater and Lesser Antilles, as well as the Caribbean coast of Venezuela and Central America, claiming them for the Spanish Empire.