Harper Lee's novel To Kill a Mockingbird is a work of fiction, but draws heavily on her own childhood experiences. The character of Scout Finch is based on Lee herself, who used to watch her father testify in court from a balcony in the courthouse. The novel is set in a small Alabama town much like the one Lee grew up in. In fact, it has been suggested that Maycomb is a false name for Lee's hometown of Monroeville. The character Dill is based on Lee's childhood friend and fellow author, Truman Capote. Similarly, the Radleys are based on a reclusive family who lived in the town Lee grew up in.
Having grown up in the pre-Civil Rights era South, Lee was certainly no stranger to the kind of racial injustice Black Americans faced. One of the major plot arcs-- the case of Tom Robinson and Mayella Ewell-- is presumed to have been based on a similar case which occurred near Monroeville when Lee was a child.
Though To Kill a Mockingbird is a work of fiction, Lee has stated that she believes authors should write about things they know to be true, which is why she drew so heavily from her own experiences and feelings.