The date of birth of a person encapsules a lot about his/her identity, characteristic and personality. In birth date astrology this information is the key to all the answers you are ever going to need. The birth date is used by the Jyotishis (astrologers) for the Naam-Karan(selecting an appropriate name) based on the positions of stars and planets on the respective time of birth of the person. Date of birth in addition with place and time of birth, when combined give us the Kundli (Natal Chart) of the person.
Astrology is a science which correlates the events on earth with the movements of the celestial bodies like sun, moon, stars and planets. So the positions of stars , the positions of the celestial bodies helps in understanding the dasha predictions, sade sati details, nakshatra phal, influence of planets and varshphal combinedly given by the kundli. All these predictions start from your birth date astrology