Astrology refers to any of several systems, traditions or beliefs in which knowledge of the apparent positions of celestial bodies and related information is held to be useful in understanding, interpreting and organizing knowledge about personality, human affairs and terrestrial events. A practitioner of astrology is called an astrologer or, less often, an astrologist. Historically the term mathematicus was used to denote a person proficient in astrology, astronomy, and mathematics.

The word "astrology" is derived from the Greek αστρολογία, from άστρον, astron, ("star") and λόγος (logos), which has a variety of meanings generally related to "systematic thought or speech." Logos is written in English as the suffix -ology, "study or discipline."

Although the two fields share a common origin, modern astronomy as practiced today is not to be confused with astrology. While astronomy is the scientific study of astronomical objects and phenomena, astrology is the attempt to correlate the apparent position of those objects with earthly and human affairs. Astrology is variously considered by its proponents to be a symbolic language, a form of art, science or divination.Critics, including the scientific community where it has commented, consider it a pseudoscience.