Bill is the Weasleys' oldest child. We don't see much of him in Book 5, though we do hear rumors from Fred and George that Bill has a new girlfriend, the French exchange student Fleur Delacour. Bill works for Gringotts, the goblin bank. He has been stationed in Egypt as a curse breaker for the last several years, but he has come back to England on a desk job. Bill has accepted this less fun position so that he can join the Order of the Phoenix. It's Bill who passes the Order the information that the goblins may consider joining Voldemort if they don't get certain rights they've been lobbying for from the Ministry of Magic. And considering the Ministry's current institutional bigotry, it seems unlikely that they'll get any kind of equal rights any time soon.