It is a person who cooks for a living. There are schools in which chefs are trained in various methods and styles of cooking. In addition, there are also styles of cooking, for example, the gourmet kitchen, French or Mexican food. Every cook prints his style in the food.
The more information you have at your disposal the better your cooking results will be. The Farm Journal's Choice Chocolate Recipes Cookbook-Pocketbook specializes in "chocolate".