Button: A button is a small device that is used to control or activate a function or operation. It is typically pressed or pushed to initiate a specific action or command.Signal Lamp: A signal lamp is a type of indicator that provides visual feedback or information. It is typically used to indicate the status or condition of a device or system, such as whether it is on or off, active or inactive.Main Switch: A main switch is a large, typically toggle or rotary switch that is used to control the power supply to a device or system. It is used to turn the power on or off, providing a convenient and safe way to control the electrical supply.