A car cigarette lighter consists of a coil of nichrome wire heated until it glows by a strong electrical current. When the driver pushes in the cigarette lighter, it presses the device into an electric receptacle, allowing the current to heat the coil. Once the lighter is hot, a metallic strip bends away, allowing the device to pop back out for use.
In addition to lighting cigarettes, the electric receptacle can also be used to power small electrical devices. Specialized adapter plugs fit into the receptacle and touch the contact points inside, completing a circuit and drawing power for the attached device. Global Positioning System devices, cell phones and other portable electronics often come with cigarette-lighter adapters allowing users to charge their batteries while driving. Another common use of the receptacle is to power small air compressors to allow drivers to re-inflate tires without needing to call for assistance.
The downward trend in smoking has led some car manufacturers to consider replacing the usual cigarette lighter socket with a USB socket or standard electric socket, allowing users to power devices without needing an adapter. In these cases, the cigarette lighter is usually still available as an option but no longer comes as part of the car's default package.