Astrology (from Greek astron, "constellation, star";logia) is a group of systems, traditions, and beliefs in which knowledge of the apparent relative positions of celestial bodies and related details is held to be useful in understanding, interpreting, and organizing information about personality, human affairs, and other terrestrial matters. A practitioner of astrology is called an astrologer or an astrologist. Numerous traditions and applications employing astrological concepts have arisen since its earliest recorded beginnings in the 3rd millennium BC. It has played a role in the shaping of culture, early astronomy, and other disciplines throughout history.