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 utensil are made for each task. 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 utensil in a household kitchen varies with time and the style of cooking. The kitchen utensils were made of iron and steel, copper, nickel, silver, tin, clay, earthenware, and aluminum.