Jyotish ["the science of illumination"] has been practiced in India for thousands of years. The study of jyotish is considered a requisite aspect of an orthodox Vedic education and has been passed down along an unbroken teacher-student lineage.
A jatakam [birth chart or horoscope: chart or diagram representing the positions of planets at the time of an event, such as the moment of a person's birth] is prepared based on one's birth date, birth time and birth location and a jyotishi [Vedic astrologer] can interpret the horoscope to help guide us as we move through the various phases of life. For example, by analyzing the jatakam, an experienced and virtuous jyotishi can interpret our potential for success or failure with regards to various undertakings. They can also help us to determine astrologically auspicious times to commence important new activities, such as moving into a new house, getting married or starting a new business venture, etc. The horoscope at the commencement of any activity is important because it bears influence on the success of that activity. The horoscope can offer insight into our psychological tendencies and strengths as well.
Another important aspect of jyotish is to help remove various obstacles we may be facing in life-be they financial, social, professional, medical or otherwise. Analyzing the jatakam, the jyotishi is given a glimpse into our prarabdha karma-the positive and negative circumstances fated to arise in our life based upon the various virtuous and selfish actions we've performed in past lives. The Jyotishi can then recommend certain remedial measures that can be performed to mitigate negative karma to varying extents. In this way, we can find relief from difficulties we are currently facing and even prevent other difficulties from even arising. Of course, there are times when the karmic imprint is too severe for either rituals or remedial measures, at which point we have no choice but to accept our situation.