The cosmos is a vast clock - wheels within wheels within wheels to which we all respond. A picture of the sky at the moment of your birth.
An Astrological Chart is a time slice of this vast cosmic performance. The moment of birth is a significant moment to 'stop the clock' and examine and study the cosmic arrangement. Any important event is worth a cosmic snapshot. Some important dates are birth, marriage, children, moves, etc. Any moment in time when one makes a change in their life is worth having a chart cast for it.
By studying the planetary arrangement for a given moment in time the Astrologer can gain an accurate picture of what has happened on Earth at that moment. This is what Astrology is all about.
The analysis of these important moments is very complex. The math needed to erect a horoscope is tedious and time-consuming. (When I first began to study Astrology in 1975 we didn't have computers and we had to compute charts by hand. Today, we have elaborate computer programs that construct charts instantly.) After a chart is constructed is when the REAL work begins. Proper interpretation of an Astrological Chart helps us to see ourselves and life in a greater perspective, to obtain the big picture. Interpretation of your chart gives very specific information to direct the events of your life with greater success.
Astrology does not have all the answers and is not a cure all. It is just one of many tools available for you to use in order to better orchestrate the direction of your life. In all cases, Astrology presents you options. The choice you make is up to you alone. You ALONE are the captain of your ship. Astrology merely provides a more complete map for you to set sail by.