what was the exposition in the book

The exposition tells me that Mathilde is born to a low-class family; with no money for a dowry, she is married to Monsieur Loisel, a clerk from the Board of Education. Mathilde–now Madame Loisel–had always felt like she should have been upper class, and is unhappy in her married life: she hates their home, their food, and her lack of fine clothing and jewelry.