Astrology is a tool that has been used for many centuries and is said to be able
to tell us who we are and where we are going based purely on the alignment of those planets at the time of our birth. However, forget what you see in the 'daily horoscopes' which are only a broad interpretation of planetary aspects, to really know who you are, why you are and where you are going, you need to see the information EXACTLY as it was on the day, hour and minute that you entered this world.
An Astrologer draws up a Birth Chart using tablets of data (or nowadays, a computer) and will work out where all the planets were at the time of your birth. Your 'sun sign' will fall into one of twelve Zodiac signs depending on what time of the year you were born. However, your 'rising sign' and other celestial events at that time is what determines you as a character rather than JUST your sun sign.
To get a full reading, an Astrologer will look at the twelve houses and see where your life fits into those houses - from that, a frighteningly accurate reading can be given, not only of your past, your character, your strenths and weaknesses - but even what you are likely to encounter in your future.