Mother Goddesses have been worshiped at all the times of history by the Hindus. They were mostly worshiped as the spouses of the Gods. From Harappa period to Gupta Period, their worship was only little known. Only in the Middle ages they emerged from obscurity as the upper classes of society began worshiping them.
She was considered as the Sakti, the strength or potency of her male counterpart. While the God was inactive and transcendent, she was active and immanent.
By Gupta period, many of these Goddesses acquired their own independent identity and began to be venerated at special temples. Even today their cult is most strong in Bengal and Assam.
Chief form of the mother Goddess is Parvati, the wife of God Siva. Parvati means the daughter of mountain. Other names are Mahadevi- the great goddess, Sati- the virtuous, Gauri- The fair one, Annapurna- giver of much food, or simply the mother (Mata) or Ammai as in Tamil.
The mother goddess has another form which is grim aspect. Here she is known as Durga- inaccessible, Kali- the black one and Chandi- the fierce. In Tamilnadu, another goddess called Koravai- the war goddess who like Kali danced among the slain on the battlefield and ate their flesh.
In her fierce aspect she is depicted as a horrible hag, frequently having many arms in which she holds many weapons, a red tongue lolling from her mouth and sometimes as a stern beautiful woman riding and lion and shown slaying a buffalo-headed demon.
She has gentle aspect in which she is a beautiful woman sitting along with her husband Siva. As Lord Siva is worshipped in the form of a phallic emblem, she is worshipped as a Yoni emblem.
There is a legend, Parvati in her early incarnation was born as Sati to sage Daksha who gave her hand very grudgingly to Lord Siva. But he never missed any opportunity to humiliate Siva.
During one such occasion in which a puja was being conducted, only she was invited by her father. In a fit of rage, she flung herself into flames. Siva became so numb with pain on her death that he carried the dead body of Sati all the times.
It was feared that if Siva began his cosmic dance of Tandava whole universe shall collapse. So Vishnu cut the body of Sati into many smaller parts and scattered them all over the earth. The places are called pithas or sacred shrines.