A bain-marie is a French term for a type of cookware used to gently and gradually heat, or to keep warm for long periods. It is not meant for cooking, but to keep food such as delicate sauces warm and separate from the boiling water in the bottom part. Term is old, perhaps originating with the alchemists who noticed sea water boiled at a high temperature and didn't evaporate quickly.(maris in French means the sea and bain means a bath). It is designed a little differently than a double-boiler so the water cannot flow into the pan with the food. There are single bain marie pans as well as ones designed to hold several pots at once.