Prediction through Dasha System is the chief objective of Predictive Astrology. Maharshi Parashar has mentioned 43 types of Dashas in his "Brihat Parashar Hora Shastra"..... Besides, the Ashtottari and Yogini Dashas have also been narrated briefly. Vimshottari Dasha system is based on constellation In following manner.
All above three parts are supplements of each other. Yoga is most important among all three parts. Period sub-period of dasha may give results according to yoga and transit is also react with dasha.