Western astrology is the system of astrology most popular in Western countries. Western astrology is historically based on Ptolemy's Tetrabiblos (2nd century AD), which in turn was a continuation of Hellenistic and ultimately Babylonian traditions.
Western astrology is largely horoscopic, that is, it is a form of divination based on the construction of a horoscope for an exact moment, such as a person's birth, in which various cosmic bodies are said to have an influence. Astrology in western popular culture is often reduced to sun sign astrology, which considers only the individual's date of birth (i.e. the "position of the Sun" at that date).
Because astrology has failed in predictions when under scientific tests, it is generally regarded as pseudoscientific.