During his first trip to Hogwarts, Harry purchases some Chocolate Frogs. Inside, he discovers Dumbledore's card which will later serve as an instrumental source of information to assist Harry in his discovery of Voldemort's plot to steal the Philosopher's Stone.
Dumbledore obtained the Elder Wand after defeating the dark wizard Grindelwald who had come to possess it. After his defeat, Grindelwald was imprisoned in the top-most cell of Nurmengard and remained there, growing emaciated and toothless, until the events of Harry Potter and the Deathly Hallows when Voldemort arrives, seeking the Elder Wand.
The Order of the Phoenix is a secret organization founded by Albus Dumbledore to fight Lord Voldemort and his Death Eaters. The Order lends its name to the fifth book of the series, Harry Potter and the Order of the Phoenix.
When Harry arrives at Hogwarts, Dumbledore tells him about the Mirror of Erised which shows the viewer his heart's desire, claiming that when he looks into it, he sees himself "holding a pair of thick, woollen socks." Harry later recalls in the final book that this was probably the only dishonest answer Dumbledore ever gave him.
A powerful curse was placed on Marvolo Gaunt's Ring as a defense against anyone who might try to destroy it. Although the curse was designed to kill anyone who tried to wear the ring, Snape was able to limit the curse to Dumbledore's hand which shriveled and turned black.