In astrology there is something known as your big three, this is your sun, moon and rising sign.
For most people, your sun sign is pretty easy to figure out. It is the sign that the sun was in (the astrological season) when you were born. All that you have to know to calculate your sun sign in your date of birth.
A way to think about your sun sign and how it will present in your life is to imagine your sun sign as an indicator of the themes and events that will present themselves to you in this lifetime.
Your moon sign is a little bit trickier to figure out. The moon changes signs about every 2.5 days, so to find your moon sign, you will most likely need to input your birth time into astrology software. Your moon sign is the sign that the moon was in at the moment of your birth.
Your moon sign can relate to your emotions and the circumstance that will arise in your lifetime.
Rising Sign or Ascendant
Your rising sign is determined by what sign was on the eastern horizon at the moment of birth. To calculate your rising sign, you need to know the exact moment and location of birth as this sign can shift every few hours.
Your rising sign is important because it can be thought of as the lens through which you experience your life. Your rising sign rules the first house of your birth chart--identity, appearance and personality.
Knowing your rising sign is important because it determines that house placement of planets in your birth chart. Whenever you read your horoscope, you always want to read for your rising sign.