In cooking, a sauce is a liquid mixture added to another food for flavour. Sauces are not normally eaten by themselves; they add flavour, moisture, and visual appeal to another dish. Sauces are an essential element in cuisines all over the world.
The main sauces of French cuisine are built on a basis of roux, which is just flour and the liquid part of butter. Examples from Italian cuisine are the cream and ham sauce called carbonara; the ground meat sauce called bolognese, and the herbs and garlic sauce called pesto.
Sauces may be used for savoury dishes or for desserts. They can be prepared and served cold, like mayonnaise, prepared cold but served lukewarm like pesto, or can be cooked like bechamel and served warm or again cooked and served cold like apple sauce.
Some sauces are commercial products like Worcestershire sauce, HP sauce, soy sauce or ketchup. In French cuisine they are freshly prepared by the chef. Sauces for salads are called salad dressing. A cook who specializes in making sauces is a saucier.