Screws are fasteners used to hold objects together, and they come in various types, each designed for specific applications. Common types include wood screws, which have coarse threads for gripping wood, and machine screws, which are used with nuts or tapped holes in metal. Other types include self-tapping screws, which create their own hole, and sheet metal screws, designed for fastening metal sheets. The head of a screw can also vary, with types like flat head, pan head, and hex head offering different driving methods and aesthetic appearances. Additionally, screws can be made from various materials, such as stainless steel for corrosion resistance or brass for decorative purposes.