Numerous traditions and applications employing astrological concepts have arisen since its earliest recorded beginnings in the 3rd millennium BC. Astrology has played an important role in the shaping of culture, early astronomy, the Vedas, and various disciplines throughout history. In fact, astrology and astronomy were often indistinguishable before the modern era, with the desire for predictive and divinatory knowledge one of the motivating factors for astronomical observation. Astronomy began to diverge from astrology after a period of gradual separation from the Renaissance up until the 18th century. Eventually, astronomy distinguished itself as the empirical study of astronomical objects and phenomena, without regard to the terrestrial implications of astrology.

The word "astrology" comes from the Latin term astrologia ("astronomy"), which in turn derives from the Greek noun αστρολογία: ἄστρον, astron ("constellation" or "star") and -λογία, -logia ("the study of").

Core beliefs

The core beliefs of astrology were prevalent in parts of the ancient world and are epitomized in the Hermetic maxim, "as above, so below". Tycho Brahe used a similar phrase to summarize his studies in astrology: suspiciendo despicio, "by looking up I see downward". Although the principle that events in the heavens are mirrored by those on Earth was once generally held in most traditions of astrology around the world, in the West there has historically been a debate among astrologers over the nature of the mechanism behind astrology. The debate also covers whether or not celestial bodies are only signs or portents of events, or if they are actual causes of events through some sort of force or mechanism.