A kitchen utensil is a small hand held tool used for food preparation. Common kitchen tasks include cutting food items to size, heating food on an open fire or on a stove, baking, grinding, mixing, blending, and measuring; different utensils are made for each task. A general purpose utensil such as a chef's knife may be used for a variety of foods; other kitchen utensils are highly specialized and may be used only in connection with preparation of a particular type of food, such as an egg separator or an apple corer. Some specialized utensils are used when an operation is to be repeated many times, or when the cook has limited dexterity or mobility. The number of utensils in a household kitchen varies with time and the style of cooking.