Food preparation is such a routine activity that we often do not question the process. For example, why do we cook as we do? Why do we eat certain foods and avoid other perfectly edible ingredients? To help answer these questions, it is extremely important to study the chemical changes that food undergoes during preparation; even simply cutting a vegetable can lead to enzymatic reactions. For many years, these molecular transformations were neglected by the food science field. In 1988, the scientific discipline called "molecular gastronomy" was created, and the field is now developing in many countries. Its many applications fall into two categories. First, there are technology applications for restaurants, for homes, or even for the food industry. In particular, molecular gastronomy has led to "molecular cooking", a way of food preparation that uses "new" tools, ingredients, and methods. According to a British culinary magazine, the three "top chefs" of the world employ elements of molecular cooking. Second, there are educational applications of molecular gastronomy: new insights into the culinary processes have led to new culinary curricula for chefs in many countries such as France, Canada, Italy, and Finland, as well as educational programs in schools. In this Account, we focus on science, explain why molecular gastronomy had to be created, and consider its tools, concepts, and results. Within the field, conceptual tools have been developed in order to make the necessary studies. The emphasis is on two important parts of recipes: culinary definitions (describing the objective of recipes) and culinary "precisions" (information that includes old wives' tales, methods, tips, and proverbs, for example). As for any science, the main objective of molecular gastronomy is, of course, the discovery of new phenomena and new mechanisms. This explains why culinary precisions are so important: cooks of the past could see, but not interpret, phenomena that awaited scientific studies. For French cuisine alone, more than 25,000 culinary precisions have been collected since 1980. The study of the organization of dishes was improved by the introduction of a formalism called "complex disperse systems/nonperiodical organization of space" (CDS/NPOS). CDS describes the colloidal materials from which the parts of a dish are made; NPOS provides an overall description of a dish. This formalism has proven useful for the study of both scientific (examining phenomena to arrive at a mechanism) and technological (using the results of science to improve technique) applications. For example, it can be used to describe the physical structure of dishes (science) but also to examine the characteristics of classical French sauces (technology). Many questions still remain in the field of molecular gastronomy. For example, one "Holy Grail" of the field is the prediction of physical, biological, chemical, and organoleptic properties of systems from their CDS/NPOS formula. Another issue to be worked out is the relationship between compound migration in food and chemical modifications of those migrating compounds. These questions will likely keep scientists busy in the near future.