To get started, you need to know a few key details about yourself: your birth date and time, and where you were born. With this info alone, an astrologer (with the help of astrology software , of course) can map out which sign each astral body happened to be in at the moment of your birth. You're probably most familiar with your sun sign, or the sign that the sun happened to be aligned with when you were born; that's the one we identify with — the one we read horoscopes for.