What is "gratin"?

Gratin is a dish made with a layer of cooked ingredients that is topped with a layer of cheese or breadcrumbs and then baked until golden brown. It is typically made with potatoes, but can also be made with other vegetables or meats. It is a popular dish in French cuisine and is enjoyed all over the world. Additionally, it can be served as a main dish or as a side dish. It is usually served hot, but can also be served cold.