What is amuse bouche?

An amuse bouche (/ˌɑːˈmjuːz ˈbuːʃ/; French for 'mouth amuser') is a one-bite hors d'oeuvre: a small, delicate bite of food, generally served before a meal. Amuse-bouches are often served in a single bite, and usually without silverware. While often served at a restaurant as a complimentary dish on the house for the purpose of "amusement" or as an opener to the meal, they are also widely used as part of cocktail parties and banquets.