A strainer is a kitchen utensil with a perforated or mesh bottom used to strain liquids or semiliquids, or to sift dry ingredients such as flour or confectioners' sugar. Strainers, also called sieves, come in a variety of sizes, shapes and mesh densities. There are flat-bottomed, drum-shaped strainers with interchangeable meshes of different coarseness, as well as those that are bowl-shaped and some that are conical. Strainers are made of various materials including stainless steel, tinned steel and aluminum. The better ones have strong handles and frames and contain hooks for resting the strainer on top of pots or bowls.