Emile Zola, along with fellow novelists Honore de Balzac and Gustave Flaubert, was an early realist in French literature. In novels such as Flaubert's Madame Bovary and Zola's Nana, sex and violence were examined with vivid clarity. These realists soon adopted the word naturalism to describe their writings.

Zola's novels were attacked and even banned for their frankness and sordid detail, causing quite a bit of controversy in their day, with their strong emphasis on the unpleasant and unglamorous side of life. The underbelly of 19th century life was a theme for several of its authors, notably Dickens in English. Because of its film versions (which are considerably toned down) and its controversial subject matter, Nana is Zola's best known novel. It is the story of a prostitute in Paris just before the Franco-Prussian War of 1870.