There are two products available to change electric current - one is a converter and the other is a transformer. THere are also two kinds of appliances - electric and electronic. Electric appliances are simple heating devices and those products with universal motors. Some examples are hot pots, hair dryers and electric blankets. Electronic appliances are those products with a chip or circuit.
Some examples are radios, camcorder rechargers and computers.
A converter is designed to be used ONLY with electric appliances such as hot pots and hair dryers. The transformer ais designed to be used with electronic appliances such as camcorder rechargers and radios AND electric appliances. Converters and transformers can either be step down or step up. Step down means changing 220v current to 110v so that 110v appliances can be used in 220v countries. Conversely, step up means changing 100v current to 220v so that 220v appliances can be used in 110v countries.