The power button is a control mechanism found on electronic devices, such as computers, televisions, and smartphones. Its primary function is to turn the device on or off. When pressed, it sends a signal to the device's internal components, initiating the startup or shutdown process. In many devices, the power button may also serve additional functions, such as putting the device into sleep mode or restarting it. The design and location of the power button can vary widely, but it is typically marked with a symbol that resembles a circle with a vertical line, indicating its purpose clearly to users.