She's the daughter of Ra, and sister of Bastet, Hathor, Sekhmet, Shu, and Tefnut.
Consorts & Children:
She's the wife of Thoth, god of knowledge and writing.
She's often depicted as a feather or a woman wearing an ostrich feather in her hair, holding a scepter in one hand and an ankh in the other.
Notable Stories Involving Her:
In the Duat, the Egyptian underworld, it is Ma'at's feather that is weighed against the heart (believed to contain the soul) of the deceased to determine if the deceased is worthy of entering Aaru (Egyptian heaven), as depicted in the Book of the Dead; those who fail are devoured by Ammit, a female demon that has the body of both a lion and hippopotamus and the head of a crocodile.
SOURCES: Wikipedia and Encyclopedia Mythica