Dasha
A dasha is a planetary period: Vedic astrology divides a life or a chart's timeline into chapters, each ruled by a planet.
What it is
The Vimshottari dasha system splits a 120-year cycle into nine planetary periods of fixed length: Sun 6 years, Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19, Mercury 17, Ketu 7, Venus 20. Each major period (mahadasha) contains sub-periods (antardasha) of all nine planets. Where the cycle starts depends on the Moon's nakshatra at birth.
How the tradition reads it
The planet ruling the current period sets the background tone. Transits then trigger events within that background. A chart in a strong Jupiter period is read differently from one in a Saturn period, even under the same sky.
In AstroFinex
Each instrument has its own natal chart, from its launch or listing date, and the engine computes its dasha timeline from it. The current period is shown with the instrument's reading.