During Navratri, people worship Goddess Durga. For nine days, the idol of Goddess Durga is established in the house and the temple. She is worshipped for nine days and people observe fast for nine days. In these nine days, nine different forms of Goddess are worshipped. On 29th September 2019, it is the first day of Navratri.
There are two reasons behind the celebration of Navratri Festival in the Scriptures. According to the first legend, there was a demon named Mahishasura who was a great devotee of Brahma Ji. He received a blessing by doing hard penance of Brahmaji. In this boon, no deity or human being could kill him. As soon as he received the boon, he became very cruel and began to threaten people in the three worlds. Frightened by his terror, the deities, along with Brahma, Vishnu and Mahesh, gave birth to Durga as Mss Shakti. A fierce war broke out between Goddess Durga and Mahishasur for nine days and on the tenth day, Goddess Durga assassinated Mahishasur. This day is celebrated as the triumph of evil over good.
According to another story, The Lord Shri Ram had worshipped the goddess Bhagwati before attacking Lanka and won the war with Ravan. In Rameswaram, he worshipped the Goddess for nine days. Happy with his devotion, the Goddess gave Ram the blessing of victory in Lanka. On the tenth day, Lord Shri Ram conquered Lanka by defeating King Ravan in the war. This day is known as Vijay Dashmi. This is the reason for celebrating Navratri.