Use a plug adapter so that you can safely use devices from the U.S., where the standard voltage is 120V, in international destinations such as Europe, the Middle East and Australia, where 220V is standard. Plug adapters also take into account the differently shaped and sized prongs of plugs on electrical devices. Obtain a "universal" plug adapter that adjusts to accommodate any plug in any destination around the world.
Plug your device tightly into into the adapter.
Adjust the switch -- if you have a universal adapter -- so the adapter's plug prongs match the outlet in front of you. The switch is labeled by location, so if you're in London, set it to "UK."
Insert the adapter's plug into the wall socket and wait for power to reach your device. When you are finished using the device, unplug the adapter, then unplug the device from it.
A universal adapter includes a switch that allows you to change the shape of the adapter to fit into different types of wall sockets. Although a universal adapter is slightly more costly than one meant for a specific destination, it is useful everywhere you travel.
Do not plug a 120V device directly into a 220V wall socket, even if the plug shape and size are identical. Although goods sold in the U.S. but available around the world sometimes accommodate 220V voltages -- iPods, for example -- other devices can be destroyed by such high voltages. When in doubt, use a converter.