This article is about the preparation cooking with frozen leeks food. For a general outline, see Outline of food preparation. For varied styles of international food, see cuisine.

Cooking, cookery, or culinary arts is the art, science and craft of using heat to prepare food for consumption. Types of cooking also depend on the skill levels and training of the cooks. Cooking is done both by people in their own dwellings and by professional cooks and chefs in restaurants and other food establishments. Preparing food with heat or fire is an activity unique to humans. Archeological evidence of cooking fires from at least 300,000 years ago exists, but some estimate that humans started cooking up to 2 million years ago.

The expansion of agriculture, commerce, trade, and transportation between civilizations in different regions offered cooks many new ingredients. Phylogenetic analysis suggests that early hominids may have adopted cooking 1. Recently, the earliest hearths have been reported to be at least 790,000 years old. Communication between the Old World and the New World in the Columbian Exchange influenced the history of cooking. In the seventeenth and eighteenth centuries, food was a classic marker of identity in Europe.

In the nineteenth-century “Age of Nationalism” cuisine became a defining symbol of national identity. The Industrial Revolution brought mass-production, mass-marketing, and standardization of food. Factories processed, preserved, canned, and packaged a wide variety of foods, and processed cereals quickly became a defining feature of the American breakfast. This section does not cite any sources.

Most ingredients in cooking are derived from living organisms. Vegetables, fruits, grains and nuts as well as herbs and spices come from plants, while meat, eggs, and dairy products come from animals. Mushrooms and the yeast used in baking are kinds of fungi. Naturally occurring ingredients contain various amounts of molecules called proteins, carbohydrates and fats.

They also contain water and minerals. Cooking involves a manipulation of the chemical properties of these molecules. The interaction of heat and carbohydrate is complex. Long-chain sugars such as starch tend to break down into more digestible simpler sugars. An emulsion of starch with fat or water can, when gently heated, provide thickening to the dish being cooked.

In European cooking, a mixture of butter and flour called a roux is used to thicken liquids to make stews or sauces. Types of fat include vegetable oils, animal products such as butter and lard, as well as fats from grains, including maize and flax oils. Fats are used in a number of ways in cooking and baking. Edible animal material, including muscle, offal, milk, eggs and egg whites, contains substantial amounts of protein. Water is often used to cook foods such as noodles. Cooking often involves water and water-based liquids. Alternatively, the foods themselves can release water.