The start of the European colonization of the Americas is typically dated to 1492. However, L'Anse aux Meadows in the Canadian province of Newfoundland and Labrador is much older. Dating from 1000AD, it is the only known site of a Norse or Viking village in Canada, and in North America outside of Greenland. L'Anse aux Meadows remains the only widely accepted instance of pre-Columbian trans-oceanic contact and is notable for its possible connection with the attempted colony of Vinland established by Leif Ericson around the same time period or, more broadly, with Norse exploration of the Americas.

In 1492, a Spanish expedition headed by Christopher Columbus sailed to America to sell, buy, and trade rich spices and other goods. European conquest, exploration, and large-scale exploration and colonization soon followed. This first occurred along the Caribbean coasts on the islands of Hispaniola, Puerto Rico and Cuba, and after 1500 extended into the interiors of both North and South America. In 1497, sailing from the north on behalf of England, John Cabot landed on the North American coast, and a year later, Columbus's third voyage reached the South American coast.

The Americas, or America, are lands in the Western hemisphere, also known as the New World.

In the English language, the Americas refers to the landmasses of North America and South America with their associated islands and regions, whereas America, in current usage, usually refers to the United States of America.

The Americas cover 8.3% of the Earth's total surface area (28.4% of its land area) and contain about 13.5% of the human population (about 900 million people).

The specifics of Paleo-Indian migration to and throughout the Americas, including the exact dates and routes traveled, are subject to ongoing research and discussion. The traditional theory has been that these early migrants moved into the Beringia land bridge between eastern Siberia and present-day Alaska around 40,000–17,000 years ago, when sea levels were significantly lowered due to the Quaternary glaciation. These people are believed to have followed herds of now-extinct pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets. Another route proposed is that, either on foot or using primitive boats, they migrated down the Pacific Northwest coast to South America. Evidence of the latter would since have been covered by a sea level rise of hundreds of meters following the last ice age.

The historical phenomenon of colonisation is one that stretches around the globe and across time, including such disparate peoples as the Hittites, the Incas and the British. European colonialism, or imperialism, began in the 15th century with the "Age of Discovery", led by Portuguese and Spanish exploration of the Americas, and the coasts of Africa, the Middle East, India, and East Asia. During the sixteenth and seventeenth centuries, England, France and Holland established their own overseas empires, in direct competition with each other. The end of the eighteenth and early 19th century saw the first era of decolonization when most of the European colonies in the Americas gained their independence from their respective metropoles. Spain and Portugal were irreversibly weakened after the loss of their New World colonies, but the Kingdom of Great Britain (after the union of England, Wales, and Scotland), France and Holland turned their attention to the Old World, particularly South Africa, India and South East Asia, where coastal enclaves had already been established. The industrialization of the nineteenth century led to what has been termed the era of New Imperialism, when the pace of colonization rapidly accelerated, the height of which was the Scramble for Africa, in which Belgium was a major and Germany a lesser participant. During the twentieth century, the overseas colonies of the losers of World War I were distributed amongst the victors as mandates, but it was not until the end of World War II that the second phase of decolonization began in earnest. In 1999 Portugal returned the last of Europe's colonies in Asia, Macau, to China, ending an era that had lasted six hundred years.