In North America, parts of South America and a few other places, a 110 volt 60 hertz standard is used. For most of the rest of world, 220 volts 50 hertz is the standard.

When appliances from 110 volt countries need to be used in 220 volt countries, a “Step-Down” voltage converter is needed. When appliances from 220 volt countries need to be used in 110 volt countries, a “Step-Up” voltage converter is needed.