The word ratatouille comes from Occitan ratatolha and the recipe comes from Occitan cuisine. The French touiller means to toss food. Ratatouille originated in the area around present day French Provence Occitan Provença.
Ratatouille is usually served as a side dish, but also may be served as a meal on its own. Tomatoes are a key ingredient, with garlic, onions, zucchini, eggplant, bell peppers, marjoram and basil, or bay leaf and thyme.