The beginning of the 1st house is a significant element of understanding your personality. Along with your Sun (identity) and Moon (emotions), your Ascendant is the third of the most important factors astrologers look at in analyzing your personality.
Your Ascendant, or Rising Sign, is the zodiac constellation that was rising on the Eastern horizon when you were born. It is located at the left horizontal line between the 12th and 1st houses of your natal chart. The Ascendant is based upon your time* and location of birth.
Your Ascendant is how you project yourself in life, how others see you. It's also your rose-colored glasses, the lens filter of the sign that was rising at birth.
A Virgo Ascendant may project themselves into life to be of useful service to the world. A Capricorn rising is more likely to take a cautious approach to the world than an adventure-seeking Sagittarius rising.
Knowledge of your rising sign will help you to understand why you project yourself into the world the way you do.
*If you cannot get your time of birth from a birth certificate, family member, or other government record, you can place your Sun sign on the Ascendant. This gives you a symbolic chart that provides accurate planetary placement, with only the fast-moving moon potentially in error. This is the method used for daily newspaper horoscope forecasts.