Cooking is the process of preparing food for consumption by combining ingredients and applying heat to change their chemical composition. Cooking makes food safe to eat, more digestible, nutritious, and more palatable.Cooking techniques vary widely, from grilling to baking, and can be done in many places, such as on a cooktop or in an oven.Cooking is a cultural universal and an activity unique to humans. Archeological evidence suggests that humans started cooking as long as 2 million years ago. Cooking involves the physics of heating and cooling, and the structure of matter. For example, fats like butter and oils liquefy and smoke when heated too much, while the fibers in vegetables soften and break down. Cooking healthy meals at home can support your immune system and reduce the risk of illnesses like heart disease, cancer, high blood pressure, and diabetes.