The setting of Maycomb, the Alabama town in the South where this novel is based, is important in the plot because of the way that it represents a microcosm of the world where Scout and Jem learn valuable important lessons, even though some would look upon it and consider Maycomb to be a tiny and insignificant place in Alabama. Note how Maycomb is introduced at the beginning of the book:
Maycomb was an old town, but it was a tired old town when I first knew it. In rainy weather the streets turned to red slop... Somehow it was hotter then... bony mules hitched to Hoover carts flicked flies in the sweltering shade of the live oaks on the square. Men’s stiff collars wilted by nine in the morning. Ladies bathed before noon, after their three-o’clock naps, and by nightfall were like soft teacakes with frostings of sweat and sweet talcum... There was no hurry, for there was nowhere to go, nothing to buy and no money to buy it with, nothing to see outside the boundaries of Maycomb County.
Maycomb is thus introduced both as a rather sleepy town set in a historical period before many of the advances that we enjoy today, but also as a town with old-fashioned values, and a very strict code of what it is right to do and what it is not to do, as signalled through the "stiff collars" that the men used to wear in spite of the heat, and the regular pattern and routine enjoyed by most inhabitants. As the plot develops, however, it is clear that it is precisely this strict code of what is right and wrong that Maycomb has is to be explored through its hypocrisy and the perspective of the children, Jem and Scout, who don't understand why things are done in a certain way, and have to learn to respect their elders and the way things are done in Maycomb, even if they don't like or respect the actual code or practice that they object to itself. This is shown in various ways through Jem and Scout challenging those around them as they grow up and learn about the complexities of life.