Sheathing is a protective layer applied to the exterior of a building's frame, typically made from materials like plywood or oriented strand board (OSB). It serves multiple purposes, including providing structural support, enhancing insulation, and acting as a barrier against moisture and wind. In addition to its protective functions, sheathing also creates a surface for attaching exterior finishes, such as siding or brick. Proper installation of sheathing is crucial for the overall durability and energy efficiency of a structure, making it an essential component in construction and renovation projects.