Realism and how authors like Mark Twain and F. Scott Fitzgerald give a "tell it like it is" writing in the stories. An author can only write realistically about what he/she knows.

In American literature realism, is an approach that attempts to describe life without idealization or romantic subjectivity. Realism has been mainly concerned with the commonplaces of everyday life among the middle and lower classes, where character is a product of social factors and environment is the important element in the dramatic complications.
The realism sought to explain why ordinary people behave they way they do. What, for example, fuels the ambitions of a young man who has come from the country to the city to make his fortune? Why does an apparently happily married woman dec…