Ninth day of Navratri; Durga worshipped in her most powerful form

Maha Navami is the ninth and final day of Sharad Navratri, dedicated to Siddhidatri, the ninth Navadurga, the giver of all siddhis — the perfections and powers — who is worshipped even by gods, siddhas, gandharvas and yakshas, and who, the Devi Purana says, bestowed on Shiva the half of his body that made him Ardhanarishvara. It is the day on which the Goddess's battle with Mahishasura reached its climax, and so her most powerful and victorious form is worshipped. Navami homa (havan) is offered to conclude the nine days of worship, and many families perform Kanya Puja on this day rather than Ashtami. In South India it is Ayudha Puja, when tools, instruments, vehicles and books are worshipped, and in Bengal it is Maha Navami, the last full day with the Goddess, marked by the Navami bhog and a bittersweet evening before her departure. Devotees who fasted for all nine days generally break their fast on Dashami after Navami has ended. The day is regarded as supremely auspicious for completing any spiritual practice begun at Ghatasthapana.

The Navratri fast continues through Navami; parana is done on Dashami.