Any text will use a number of different tools to communicate its purpose and themes, but in this classic the most notable literary tool that is used is the first person narration that gives it such a distinctive colour. The "I" of this story, Scout Finch, who is our narrator, begins the novel as a nearly-six-year-old, but it is the adult Scout looking back at her childhood that tells us the action of the plot. This retrospective first person narrator therefore allows for adult insights and language to be combined with the innocent perspective of a child. This allows for a greater level of introspection and reflection as the adult Scout looks back at her childhood attitudes with amusement and greater wisdom.
It is by far this narrative choice that makes the novel memorable and appealing to so many generations, as it encourages us to revisit our childhood through the eyes of somebody who is more mature and older and to compare our own state of former innocence to that of Scout's. In particular, it gives us a compelling vision of how features of society such as class and race become instilled in future generations.