The simplest switch has two pieces of metal called "contacts". When the two contacts are in contact, the current forms a loop, and when the two contacts are not in contact, the current opens. The degree of corrosion resistance of the contact metal should be considered when selecting the contact metal, as most metals oxidize to form insulating oxides that prevent the contact from functioning properly. The selection of contact metal also needs to consider factors such as its electrical conductivity, hardness, mechanical strength, cost and whether it is toxic. Corrosion-resistant metals are sometimes plated on the contacts. Generally, it is plated on the contact surface of the contact to avoid affecting its performance due to oxides. Sometimes non-metallic conductive materials, such as conductive plastics, are also used for the contact surface. In addition to the contacts in the switch, there will also be movable parts to make the contacts conductive or non-conductive. The switch can be divided into a lever switch (Toggle switch), a button switch, a rocker switch (Rocker switch), etc. according to the different movable parts. , and the movable part can also be other types of mechanical links. The main feature of the switch component is the function of turning on and off the circuit, and using this function can realize the on/off/conversion control of various electronic products and electrical equipment. The identification of the switch component in the circuit is usually divided into two parts, one part is the graphic symbol to identify the type of the switch part; the other part is the letter + number to identify the name serial number of the switch part in the circuit and other information. The simplest switch has two pieces of metal called "contacts". When the two contacts are in contact, the current forms a loop, and when the two contacts are not in contact, the current opens. The degree of corrosion resistance of the contact metal should be considered when selecting the contact metal, as most metals oxidize to form insulating oxides that prevent the contact from functioning properly. The selection of contact metal also needs to consider factors such as its electrical conductivity, hardness, mechanical strength, cost and whether it is toxic.