The Vimshottari Dasha (विंशोत्तरी दशा) is a 120-year planetary period system that maps which graha governs each chapter of your life. Your life moves through nine planets in a fixed sequence, each ruling a span of years that shapes the themes, events, and opportunities of that time. Within each major period there are four progressively finer layers of sub-periods — Antardasha, Pratyantardasha, Sookshma, and Prana — that allow timing down to the month, week, and day. The starting planet is determined by your birth Moon's Nakshatra, making accurate birth data essential.