A chef is a person who cooks professionally for other people. Although over time the term has come to describe any person who cooks for a living, traditionally it refers to a highly skilled professional who is proficient in all aspects of food preparation.

The word "chef" is borrowed (and shortened) from the French term chef de cuisine, the director or head of a kitchen. (The French word comes from Latin caput and is cognate with English "chief".) In English, the title "chef" in the culinary profession originated in the haute cuisine of the 19th century. Today it is often used to refer to any professional cook, regardless of rank.

Below are various titles given to those working in a professional kitchen and each can be considered a title for a type of chef. Many of the titles are based on the brigade de cuisine (or brigade system) documented by Auguste Escoffier, while others have a more general meaning depending on the individual kitchen.

This person is in charge of all things related to the kitchen which usually includes menu creation; management of kitchen staff; ordering and purchasing of inventory; and plating design. Chef de cuisine is the traditional French term from which the English word chef is derived. Head chef is often used to designate someone with the same duties as an executive chef, but there is usually someone in charge of them, possibly making the larger executive decisions such as direction of menu, final authority in staff management decisions, etc. This is often the case for chefs with several restaurants.

Thomas Keller (born October 14, 1955) is an American chef, restaurateur, and cookbook writer. He and his landmark Napa Valley restaurant, The French Laundry in Yountville, California, have won multiple awards from the James Beard Foundation, notably the Best California Chef in 1996, and the Best Chef in America in 1997. The restaurant is a perennial winner in the annual Restaurant Magazine list of the Top 50 Restaurants of the World.

In 2005, he was awarded the three star rating in the inaugural Michelin Guide for New York for his restaurant Per Se, and in 2006, he was awarded three stars in the inaugural Michelin Guide to the Bay Area for The French Laundry. He is the only American chef to have been awarded simultaneous three star Michelin ratings for two different restaurants.

Born at Camp Pendleton in Oceanside, California to Edward, a Marine drill instructor, and Betty Keller, a restaurateur, Thomas was the youngest of five boys. Four years after his parents divorced, the family moved east and settled in Palm Beach, Florida. In his teenage summers, he worked at the Palm Beach Yacht Club starting as a dishwasher and quickly moving up to cook. It was here he discovered his passion for cooking and perfection in a hollandaise sauce.