In To Kill a Mockingbird, who is Boo Radley, and what does he represent?

Boo Radley is a much talked about recluse, who lives in Maycomb. He never comes out of the house, and is a source of wonder and curiosity for the Finch children and Dill, who spend a lot of time trying to get him to come out. The town rumor mill has the children believing Boo is a monster, but over the course of the novel, they come to understand him..... and Boo becomes their protector. Boo represents one of the mockingbirds in the novel.