A cookie sheet, sometimes called an oven tray or baking sheet, is used to hold uncooked food items (typically cookies or bread) while baking within an oven. If it has sides, they are very low, to allow fast removal of cookies to a cooling rack. Unlike a typical pizza pan, an oven tray is rectangular and usually does not have any holes.
Baking sheets are available in non-stick materials, but these tend to overbrown cookies on the bottom before thoroughly cooking them. To avoid this, professional bakers use more evenly conductive materials, such as heavy-gauge stainless steel, covered with a sheet of parchment paper or a silicone baking mat to provide a non-stick effect without altering the sheet's effectiveness.
Many consumer alternatives, such as insulated aerobake sheets, are also available, which will cook more slowly but with similar effectiveness.
A baking sheet should be accompanied by a cooling rack of similar size which the baked goods can be quickly removed to when they are done cooking.