The nine forms of Durga are worshipped during the nine days of Navratri.
1. Sailaputri – In this form Durga is two-armed and carries a trident and lotus. Her mount is an ox or bull. Sailaputri is believed to be the rebirth of Sati, the daughter of Daksha and the wife of Lord Shiva. In her second birth she is Parvati, the daughter of Himalaya and later she became the consort of Shiva. This is one of the very first forms of Shakti and is closely associated with Lord Shiva. Shailaputri is worshipped on the first day of Navaratri.
2. Brahmacharini – In this form Durga is two-armed and carries a rosary and sacred water pot (Kamandalu). She is in a highly pious and peaceful form or is in meditation. This form of Durga is related to the severe penance undertaken by Sati and Parvati in their respective births to attain Lord Shiva as husband. Some of the most important Vratas observed in different parts of India by women is based on the strict austerities followed by Brahmacharini. She is also known as Tapasyacharini and is worshipped on the second day of Navrathri.
3. Chandraghanta – In this form Durga is 10-armed and rides a tiger. She carries pot, bow, arrow, lotus, discus, rosary, trident, mace and sword. This is a terrible aspect and is roaring in anger. This form of Durga is completely different from earlier forms and shows when provoked she can be the terrible or malevolent. Chandraghanta is worshipped on the third day of Navarathri.
4. Kushmanda – In this form Durga is eight-armed and rides on a tiger. She holds kamandalu, bow, arrow, lotus, pot containing wine, disc, rosary and a club. She is very happy in this form and it is believed that the eternal darkness ended when she smiled. And this led to the beginning of creation. Kushmanda form of Durga is worshipped on fourth day of Navratri.
5. Skanda Mata – In this form Durga is four-armed and rides on a lion. She carries lotus, kamandalu (pot) and bell. Her one hand is in blessing posture. In this form she is the mother of Lord Muruga or Subrahamniya or Kartik, who is also known as Skanda. This the motherly form of Durga and she is benevolent. Skanda Mata form of Durga is worshipped on the fifth day of Navaratri.
6. Katyayani – In this form Durga is four-armed and she carries a sword, shield and lotus. One hand is depicted as giving blessing. She rides a lion. It is believed that in this form she was born as a daughter to Sage Katya of Katya clan. This is the daughter form of Durga. She is epitome of love also won't hesitate to rise up in anger. Katyayani form of Durga is worshipped on the sixth day of Navrathri.
7. Kalaratri – In this form Durga is four-armed and rides a donkey. She carries sword, trident and noose. With one hand she blesses. In this form she is dark and repulsive in appearance. She is cruel and excited. This is the violent and dark side of Durga. This form primarily depicts that life also has dark side. Kalaratri form of Durga is worshipped on seventh day of Navarathri.
8. Maha Gowri – In this form Durga is four-armed and she rides on a bull or a white elephant. She carries a trident and hand-drum. Two hands are in blessing posture. She is pure and is believed to have been in the form of Mata Parvati when she did penance to get Shiva as her husband. Purity is depicted in this form of Durga. Mahagowri form of Durga is worshipped on the eighth day of Navratri.
9. Siddhidayini – In this form Durga is seated on a lotus and is four armed. She holds a lotus, mace, discus and book. In this form Durga removes ignorance and she provides the knowledge to realize That or Brahman. She is surrounded by Siddhas, Gandharvas, Yakshas, Demons and Gods who are worshipping her. The Siddhi that she provides is the realization that only She exists. Siddhidayini form of Durga is worshipped on the ninth day of Navaratri.