By Rick Steves
Europe's electrical system is different from ours in two ways: the voltage of the current and the shape of the plug.
American appliances run on 110 volts, while European appliances are 220 volts. Newer travel accessories and electronic gadgets are "dual voltage," which means they work on both American and European current. If you see a range of voltages printed on the item or its plug (such as "110–220"), you're OK in Europe. Some older appliances have a voltage switch marked 110 (US) and 220 (Europe) — switch it to 220 as you pack.
A few old, cheap American appliances aren't equipped to deal with the voltage difference at all, and they could be damaged or destroyed if plugged directly into a European wall outlet. In these cases, you'll need to buy a separate, bulky converter (about $30). With so many dual-voltage gadgets available, I haven't traveled with a separate converter in years. Still not sure? Travel stores offer useful advice on plugs and adapters (such as Magellan's "Electrical Connection Wizard").
Once you've dealt with the voltage, you'll have to consider the plug. A small adapter allows American-style plugs (two flat prongs) to fit into British or Irish outlets (which take three rectangular prongs) or continental European outlets (which take two round prongs). I bring both continental and British adapters (handy for long layovers at Heathrow Airport). Secure your adapter to your device's plug with electrical or duct tape; otherwise it can easily get left behind in the outlet (hotels or bed and breakfasts sometimes have a box of abandoned adapters — ask). Many sockets in Europe are recessed into the wall; your adapter should be small enough so that the prongs seat properly in the socket. If, for some reason, your adapter doesn't work in your hotel, just ask at the desk for assistance; hotels with unusual sockets will invariably have the right adapter to loan you.
Some budget hotel rooms have only one electrical outlet, occupied by the lamp. Hardware stores in Europe sell cheap three-way plug adapters that let you keep the lamp on and your camera battery and smartphone charged.
As you're packing, try to go light with your electronic gear — you want to experience Europe, not interface with it. Of course, some mobile devices are great tools for making your trip easier or better. As the lines separating smartphones, tablets, media players, cameras, GPS devices, and ereaders continue to blur, think creatively about how you might pare down the number of gadgets you bring on the road.