The concept of the Western part of Earth has its roots in Greco-Roman civilization in Europe, and the advent of Christianity. In the modern era, Western culture has been heavily influenced by the traditions of the Renaissance, Protestant Reformation, Age of Enlightenment -- and shaped by the expansive colonialism of the 15th-20th centuries. Before the Cold War era, the traditional Western viewpoint identified Western Civilization with the Western Christian (Catholic-Protestant) countries and culture. Its political usage was temporarily changed by the antagonism during the Cold War in the mid-to-late 20th Century (1947-1991).

The term originally had a literal geographic meaning. It contrasted Europe with the linked cultures and civilizations of the Middle East and North Africa, South Asia, Southeast Asia and remote Far East, which early-modern Europeans saw as the East. Today, this has little geographic relevance, since the United States and Canada are in the Americas, Russia expands to Northern Asia and Australia and New Zealand are part of Oceania.

In the contemporary cultural meaning, the phrase "Western world" includes Europe, as well as many countries of European colonial origin with substantial European ancestral populations in the Americas and Oceania.