A nail is a small metal fastener used to join materials together, typically made of steel. It has a pointed end for easy insertion and a flat head to provide a surface for hammering. Nails come in various sizes and types, including finishing nails, common nails, and brad nails, each designed for specific applications in construction and woodworking. In addition to their use in building, nails can also be found in crafting and home improvement projects. They are often used to attach items like wooden boards or furniture parts, providing a strong and durable connection.