A baked food usually (but not always) contain flour, eggs, milk and/or other fats. A cake is usually sweet, but its nature may vary from light and porous sponges to much denser fruit and nut concoctions. Cake has always been seen as somewhat of a treat, especially if it contains other flavourings. The ability to bake cakes was once seen as a necessary skill of housewives who would have one on hand, however plain, at all times. Cakes may be iced or decorated in many different ways, such as elaborate gateaux, Christmas and birthday cakes and simnel cakes, and are universally used as celebration foods. The word cake is also used to denote something that is shaped into a round with a flat top and bottom. Hence crab cakes, ice cream cakes, hot cakes and rice cakes are all cake shaped but have few of the other attributes.