Psychic astrology is one of the most commonly used psychic tools. (Unfortunately, psychic astrology is even more commonly used for superficial entertainment purposes.)
The psychic system of astrology attempts to describe the inner world of humans as it relates to the outer world in an objective manner. Amazingly, perhaps due to thousands of years old traditions, it can paint a pretty accurate picture.
The system of psychic astrology works by creating an abstract and simplified version of the world, and by observing the relations and patterns in this simplified system the psychic can make parallel observations in the real world.
What psychic astrology is not:
It's not a tool for finding out your 'fate or future written in the stars'. Besides being very inaccurate, such a closed-minded approach to psychic astrology (and life in general) can be devastating to a psychic, and is a serious misuse of this potentially valuable tool.