Western civilization traces its roots back to Europe and the Mediterranean. It began in ancient Greece, transformed in ancient Rome, and evolved into medieval Western Christendom before experiencing such seminal developmental episodes as the development of Scholasticism, the Renaissance, the Reformation, the Scientific Revolution, the Enlightenment, the Industrial Revolution, and the development of liberal democracy. The civilizations of classical Greece and Rome are considered seminal periods in Western history. Major cultural contributions also came from the Christianized Germanic peoples, such as the Franks, the Goths, and the Burgundians. Charlemagne founded the Carolingian Empire and he is referred to as the "Father of Europe". Contributions also emerged from pagan peoples of pre-Christian Europe, such as the Celts and Germanic pagans as well as some significant religious contributions derived from Judaism and Hellenistic Judaism stemming back to Second Temple Judea, Galilee, and the early Jewish diaspora; and some other Middle Eastern influences. Western Christianity has played a prominent role in the shaping of Western civilization, which throughout most of its history, has been nearly equivalent to Christian culture. (There were Christians outside of the West, such as China, India, Russia, Byzantium and the Middle East). Western civilization has spread to produce the dominant cultures of modern Americas and Oceania, and has had immense global influence in recent centuries in many ways.

Following the 5th century Fall of Rome, Europe entered the Middle Ages, during which period the Catholic Church filled the power vacuum left in the West by the fall of the Western Roman Empire, while the Eastern Roman Empire (or Byzantine Empire) endured in the East for centuries, becoming a Hellenic Eastern contrast to the Latin West. By the 12th century, Western Europe was experiencing a flowering of art and learning, propelled by the construction of cathedrals, the establishment of medieval universities, and greater contact with the medieval Islamic world via Al-Andalus and Sicily, from where Arabic texts on science and philosophy were translated into Latin. Christian unity was shattered by the Reformation from the 16th century. A merchant class grew out of city states, initially in the Italian peninsula (see Italian city-states), and Europe experienced the Renaissance from the 14th to the 17th century, heralding an age of technological and artistic advance and ushering in the Age of Discovery which saw the rise of such global European empires as those of Portugal and Spain.

The Industrial Revolution began in Britain in the 18th century. Under the influence of the Enlightenment, the Age of Revolution emerged from the United States and France as part of the transformation of the West into its industrialised, democratised modern form. The lands of North and South America, South Africa, Australia and New Zealand became first part of European empires and then home to new Western nations, while Africa and Asia were largely carved up between Western powers. Laboratories of Western democracy were founded in Britain's colonies in Australasia from the mid-19th centuries, while South America largely created new autocracies. In the 20th century, absolute monarchy disappeared from Europe, and despite episodes of Fascism and Communism, by the close of the century, virtually all of Europe was electing its leaders democratically. Most Western nations were heavily involved in the First and Second World Wars and protracted Cold War. World War II saw Fascism defeated in Europe, and the emergence of the United States and Soviet Union as rival global powers and a new "East-West" political contrast.

Other than in Russia, the European empires disintegrated after World War II and civil rights movements and widescale multi-ethnic, multi-faith migrations to Europe, the Americas and Oceania lowered the earlier predominance of ethnic Europeans in Western culture. European nations moved towards greater economic and political co-operation through the European Union. The Cold War ended around 1990 with the collapse of Soviet-imposed Communism in Central and Eastern Europe. In the 21st century, the Western World retains significant global economic power and influence. The West has contributed a great many technological, political, philosophical, artistic and religious aspects to modern international culture: having been a crucible of Catholicism, Protestantism, democracy, industrialisation; the first major civilisation to seek to abolish slavery during the 19th century, the first to enfranchise women (beginning in Australasia at the end of the 19th century) and the first to put to use such technologies as steam, electric and nuclear power. The West invented cinema, television, radio, telephone, the automobile, rocketry, flight, electric light, the personal computer and the Internet; produced artists such as Michelangelo, Shakespeare, Leonardo da Vinci, Beethoven, Vincent van Gogh, Picasso, Bach and Mozart; developed sports such as soccer, cricket, golf, tennis, rugby and basketball; and transported humans to an astronomical object for the first time with the 1969 Apollo 11 Moon Landing.

While the Roman Empire and Christian religion survived in an increasingly Hellenised form in the Byzantine Empire centered at Constantinople in the East, Western civilization suffered a collapse of literacy and organization following the fall of Rome in AD 476. Gradually however, the Christian religion re-asserted its influence over Western Europe.

After the Fall of Rome, the papacy served as a source of authority and continuity. In the absence of a magister militum living in Rome, even the control of military matters fell to the pope. Gregory the Great (c 540–604) administered the church with strict reform. A trained Roman lawyer and administrator, and a monk, he represents the shift from the classical to the medieval outlook and was a father of many of the structures of the later Roman Catholic Church. According to the Catholic Encyclopedia, he looked upon Church and State as co-operating to form a united whole, which acted in two distinct spheres, ecclesiastical and secular, but by the time of his death, the papacy was the great power in Italy:

Pope Gregory the Great made himself in Italy a power stronger than emperor or exarch, and established a political influence which dominated the peninsula for centuries. From this time forth the varied populations of Italy looked to the pope for guidance, and Rome as the papal capital continued to be the center of the Christian world.

According to tradition, it was a Romanized Briton, Saint Patrick who introduced Christianity to Ireland around the 5th century. Roman legions had never conquered Ireland, and as the Western Roman Empire collapsed, Christianity managed to survive there. Monks sought out refuge at the far fringes of the known world: like Cornwall, Ireland, or the Hebrides. Disciplined scholarship carried on in isolated outposts like Skellig Michael in Ireland, where literate monks became some of the last preservers in Western Europe of the poetic and philosophical works of Western antiquity.