Brahmacharini Devi is one of the nine Durga avatars, worshiped during Navratri.

Legend
Brahmacharini Devi is a form of the goddess Parvati also known as Tapascharini and Uma. As Goddess Parvati is a manifestation of Goddess Shakti who was born as a daughter of Raja Daksha. She is portrayed as a beautiful young woman, holding a kamandal in her left hand and rudraksha mala in her right hand, seen wearing a white saree. It signifies her simplicity and divine nature.
This form Goddess Parvati is worshiped in an unmarried form. According to a story, Goddess Sati wanted to marry Lord Shiva who was a recluse (popularly known as Vairagi). To convince Lord Shiva, she practiced immense tapas for 5000 years.
She let herself depend on fruits and leaves to live life. Living as a Brahmacharini, she left everything behind and started tapas for years without desisting. looking at her sincere practice, Lord Shiva, impressed by the devotion of this form of Goddess Parvati, agreed to marry her after thousands of years.
Since then this form of Goddess Parvati is being worshiped by unmarried girls to get. One can achieve peace and happiness for a lifetime by worshiping this form of Goddess Parvati. It is believed to be auspicious to offer milk, butter, honey, and sugar to Goddess Brahmacharini Devi.