Ancient Greek philosophy arose in the 6th century BC. Philosophy was used to make sense of the world using reason. It dealt with a wide variety of subjects, including astronomy, epistemology, mathematics, political philosophy, ethics, metaphysics, ontology, logic, biology, rhetoric and aesthetics. Greek philosophy continued throughout the Hellenistic period and later evolved into Roman philosophy.

Greek philosophy has influenced much of Western culture since its inception, and can be found in many aspects of public education. Alfred North Whitehead once claimed: "The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato". Clear, unbroken lines of influence lead from ancient Greek and Hellenistic philosophers to Roman philosophy, early Islamic philosophy, medieval scholasticism, the European Renaissance and the Age of Enlightenment.

Greek philosophy was influenced to some extent by the older wisdom literature and mythological cosmogonies of the ancient Near East, though the extent of this influence is widely debated. The classicist Martin Litchfield West states, "contact with oriental cosmology and theology helped to liberate the early Greek philosophers' imagination; it certainly gave them many suggestive ideas. But they taught themselves to reason. Philosophy as we understand it is a Greek creation".

In general, the ancient Greeks acknowledged their Egyptian forebears, and in the fifth century BCE, the philosopher Isocrates declared that the earliest Greek thinkers traveled to Egypt to seek knowledge; one of them Pythagoras of Samos, who "was first to bring to the Greeks all philosophy".

In the 21st century, research by Egyptologists has indicated that the word philosopher itself seems to stem from Egypt: "the founding Greek word philosophos, lover of wisdom, is itself a borrowing from and translation of the Egyptian concept mer-rekh (mr-rḫ) which literally means 'lover of wisdom,' or knowledge."

Subsequent philosophic tradition was so influenced by Socrates as presented by Plato that it is conventional to refer to philosophy developed prior to Socrates as pre-Socratic philosophy. The periods following this, up to and after the wars of Alexander the Great, are those of "Classical Greek" and "Hellenistic philosophy", respectively.

The convention of terming those philosophers who were active prior to the death of Socrates as the pre-Socratics gained currency with the 1903 publication of Hermann Diels' Fragmente der Vorsokratiker, although the term did not originate with him. The term is considered useful because what came to be known as the "Athenian school" (composed of Socrates, Plato, and Aristotle) signaled the rise of a new approach to philosophy; Friedrich Nietzsche's thesis that this shift began with Plato rather than with Socrates (hence his nomenclature of "pre-Platonic philosophy") has not prevented the predominance of the "pre-Socratic" distinction.

Since 2016, however, scholarly discourse has shifted from using the term "pre-Socratic philosophy" to the more neutral "Early Greek Philosophy". This change has been popularized in part by André Laks and Glenn W. Most through their comprehensive nine-volume Loeb Classical Library edition of Early Greek Philosophy. In the first volume, they distinguish their systematic approach from that of Hermann Diels, starting with the deliberate choice of terminology. They prefer "Early Greek Philosophy" over "pre-Socratic philosophy" primarily because Socrates was a contemporary of, and in some cases even preceded, thinkers traditionally labeled as "pre-Socratic" such as the Atomists.