What is Astrology ?

Astrology-
is a group of systems, traditions, and beliefs in which knowledge of the 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 2nd millennium BCE.[1] It has played a role in the shaping of culture, early astronomy, and other disciplines throughout history.

Historically, astrology and astronomy were often indistinguishable, with the desire for predictive and divinatory knowledge one of the primary motivating factors for astronomical observation. Astronomy began to diverge from astrology after a long period of gradual separation from the Middle Ages up until the 18th century, and has since distinguished itself as the scientific study of astronomical objects and phenomena, placing no significance on these phenomena's supposed astrological correlation.

Besides the most popular, natal, there are a few other types of astrology that are based on similar methods. Those are:

Astro-meteorology is predicting the weather, as well as some natural disasters such as floods, earthquakes or volcanic eruptions.
Agricultural astrology is the oldest branch. It was used to predict the best time to start the field work.
Medical astrology predicts potential health problems, and sets therapy for them.
Esoteric astrology is astrology of the soul. It uses natal charts to find out things about the spiritual conscience and spiritual development of a person.
Horary astrology finds an answer to any question according to the place and time the question was asked at (it is interesting how a question can't be asked twice, because then the answer is invalid!).
Electional astrology is a sub-class of horary astrology and it determines what time is best fitting to start some project, marriage, war and similar.
Mundane astrology makes horoscopes on the count when some country was "born", so it could predict national happenings and see their outcomes.
Astro-economics implements astrological principals to find answers to questions interesting to the financial world.
Synastry is a special branch of astrology that is comparing natal charts to find relations amongst people.
Psychological astrology uses its symbolic language to evaluate personality elements.