A nail is a small metal fastener used in construction and woodworking. It typically has a pointed end for easy insertion into materials like wood, and a flat head that prevents it from being driven all the way through. Nails come in various sizes and types, including common nails, finishing nails, and brad nails, each designed for specific applications. Nails are often used to join pieces of wood together, providing strength and stability to structures such as furniture, frames, and buildings. They can be driven in manually with a hammer or using a nail gun for faster application.