What it means
The Darakaraka is the mirror image of the Atmakaraka: where the soul significator is the planet that has travelled furthest into its sign, the Darakaraka is the one that has travelled least - the lowest degree among the ranked planets, whichever sign it sits in. 'Dara' is the Sanskrit word for spouse, and every chart has exactly one.
How it is read
It is read for partnership: the qualities a person is drawn to in a spouse, and the flavour a close relationship takes in that life. In practice it is examined alongside the 7th house and its lord and the fixed karakas for marriage (Venus, Jupiter), and often again in the Navamsa - the Darakaraka describes what you seek, the rest of the chart how the seeking goes.
What to watch for
Two cautions. It is a Jaimini technique, not a Parashari one, and schemes differ - seven planets or eight (with Rahu counted backward from thirty degrees), which can hand different calculators different answers for the same chart. And because the ranking runs on exact degrees, an uncertain birth time can swap the lowest-degree planet entirely; it describes an attraction, not a person or a prediction.