What The USA Uses:

• Electricity in the United States is at 110 or 120 volts and a frequency of 50Hz.
• Appliances in the United States typically use a double flat prong or three prong plug.

 
What Other countries Use: (Europe)

• Electricity in many countries is at 220 or 230 volts and a frequency of 60Hz.
• Appliances in those countries can use a variety of different prongs.

How to fix this:

To convert electricity you will need a converter.  Most converter reduces 220 volts to 110 volts for low wattage items such as hair dryers, irons and other devices. Some appliances come with dual voltage abilities.  For example, a Canon camera battery charger states on the back: input: 100V-240V AC 50/60Hz.  You will not need a converter to use the charger in a country that has 220 volts/60Hz.

From the previous Canon camera battery charger example, you may need an adaptor in some countries to plug the charger into the wall.  Different countries have different plug configurations.  You will need to buy the correct plug adapter that fits.

Many hair dryers, batter chargers and other small appliances have dual voltage abilities.  It will often be stated on the back of the plug.

You can often buy a converter with various plug adapters.  Buying a standard international set of plug adapters and you should be well equipped to tackle any country.