The orgins of astrology date back to possibly somewhere around 2,000 B.C. with the Babylonians. Most people's perceptions of astrology have more to do with how the media has portrayed it as - a method of fortune telling. However, astrology is not a method of fortune telling at all.
Astrologers determine tendancies and predispositions of characteristics of persons and events.
What the astrologer is actually doing is carefully looking at the chart constructed - most often the natal chart. A natal chart, sometimes called a birth chart, is a map of the heavens at the time of birth. This includes the day, month, year, time as well as the place of birth. By looking at this chart, an astrologer can deduce how a client is likely to react to situations. By comparing the planets transiting the natal chart and they aspects they make, it can also be deduced some of the likely situations that will arise in different areas of the client's life.