Glad you asked. Astrology is a series of beliefs holding that there is a relationship between astronomical phenomena and events in the human world. Western Astrology most often consists of a birth chart explaining various aspects of a person's personality and through transits and progressions of the sun, moon, and other planetary objects since the time of their birth, predict future events in their life.
Astrology has been dated to at least the 2nd millennium BCE, with roots in calendrical systems used to predict seasonal shifts and to interpret celestial cycles as signs of divine communications. A form of astrology was practised in the first dynasty of Mesopotamia (1950–1651 BCE) while Chinese astrology was elaborated in the Zhou dynasty (1046–256 BCE). Hellenistic astrology after 332 BCE mixed Babylonian astrology with Egyptian Decanic astrology in Alexandria, creating horoscopic astrology, the predominant form used in the West today.
You'd be surprised. At last count there were over 80 branches of astrology in use! Today we can work with Western astrology, Vedic, Hellenistic, Classical, Traditional, Mayan, Aztec, Chinese, Korean astrology, and many, many more.