A power switch is a button, lever, or toggle that turns an electrical device on or off by controlling whether electricity flows to it. When you press the power switch on a computer, you're completing or breaking an electrical circuit, like opening or closing a gate that electricity flows through.

Most electronic devices have a power switch somewhere: computers have one on their case, lamps have switches on their cords or bases, and video game consoles have power buttons on the front. The classic design uses a circle (meaning “off”) and a line (meaning “on”), though many modern devices just show a circle with a line through the top.

Power switches serve an important practical purpose beyond just convenience. They let devices rest when not in use, which saves electricity and prevents components from wearing out unnecessarily. They also provide safety: if something goes wrong with a device, you can immediately cut its power.

Some power switches are physical buttons you push, while others are touch-sensitive panels. Some older devices use toggle switches that flip up and down with a satisfying click. The main power switch on a building's electrical panel can shut off electricity to an entire house, which electricians use when making repairs.