In your opinion, what does the mockingbird symbolise in To Kill a Mockingbird by Harper Lee?

The mockingbird features prominently throughout Lee's novel and is used to represent innocence. Near the beginning of the novel, Atticus tells Jem and Scott that it is a "sin to kill a mockingbird." This view is later reinforced by Miss Maudie who informs the children that mockingbirds are peaceful creatures who are the epitome of goodness.  

The characters Boo Radley and Tom Robinson both represent mockingbirds. Although Boo Radley receives bad press from the neighbourhood, he is in fact an innocent man who is traumatized by events of the past and prefers to stay indoors. Likewise, Tom Robinson is a victim of racial prejudice as he is deliberately and wrongfully accused of raping a young white woman in the town. Both men are innocent victims and hurting either of them would be "a sin," just as killing a mockingbird would be.