Standard Wire Gauge (SWG) is a system used to measure the diameter of wire. It provides a standardized way to specify wire sizes, which is important for various applications in electrical and mechanical engineering. The gauge number inversely relates to the wire diameter; as the gauge number increases, the wire diameter decreases. SWG is commonly used in the United Kingdom and is essential for ensuring compatibility in electrical components and connections. Different materials, such as copper or aluminum, may have different properties, but the SWG system helps maintain consistency in wire sizing across various applications.