A lean-to shed is a simple, single-roofed structure that is typically attached to the side of an existing building, such as a house, garage, or barn. It has a slanted roof that slopes downward from the high point where it attaches to the wall of the main building, to the lower point where it meets the ground.

Lean-to sheds are often used for storing garden tools, outdoor equipment, or firewood, and can be constructed from a variety of materials, such as wood, metal, or plastic. They are generally less expensive and easier to build than stand-alone sheds, since one wall of the shed is already provided by the main building. However, the size of the lean-to shed is often limited by the size of the supporting wall, and it may not be suitable for larger storage needs.