Galadriel was a princess of the Noldor, and was a leader of the host of Fingolfin in the First Age when the Noldor were debating whether or not to return to Middle-earth.
She dwelt on Tol Sirion until she decided to move to Doriath, where she met and married Celeborn. She had one child, Celebrían, a girl who later married Elrond. She was the only Noldor Elf to survive the Wars of Beleriand, for she fled to the east with Celeborn.
During the Second Age Galadriel lived in Eregion until she founded and became the queen of Lórien. She modeled her city after Doriath, making it so that no one who entered would be allowed to leave. Galadriel did this through the power of Nenya, one of the Elven Rings which was given to her at its forging. The only force that could ever destroy Lórien was if Sauron had come forth himself.
In the War of the Ring Galadriel helped greatly the Company of the Ring by giving them many useful gifts, especially granting Frodo the Phial of Galadriel. She also resisted the temptation of the One Ring when Frodo offered it to her, and thus she was allowed to return to Valinor at the end of the Third Age, which she did.
By John Howe.