A basic French white sauce made by adding hot milk to a white roux (heated butter mixed with flour). In an early era, cream was generally used instead of milk. The roux thickens the milk into a creamy white sauce. Some sauces refer to a blonde and a white roux, the difference being the length of time the flour or mixture was allowed to cook and thus become brown, or golden tan in color. Seasonings can be added based on the type of dish served with the sauce and the flavors desired.