What is a sommelier?
Many of the finest restaurants have a "sommelier" on staff, which is the French term for cellar master or wine steward. A sommelier is a trained wine professional who can recommend wines that will well-accompany the food that is being served. A Master Sommelier is an expert who has passed four levels of examinations offered by the Court of Master Sommeliers, an international examining body. They can speak with authority the principal grape varieties used in wine making and the areas of the world where they are cultivated. A person holding a Master Sommelier Diploma is an expert not only in wines, but also spirits and other alcoholic beverages.
Tipping a sommelier directly is customary if you feel he or she spent a great deal of time discussing wine selections with you in addition to opening, pouring or decanting the wine. Keep in mind that at most restaurants, the gratuity (15% to 20% for good service; more than that for outstanding service) paid on the total bill (including the wine) is divided formulaically among the servers, sommelier, bartender and runners.