Electricity voltage varies between countries.
Over 30 countries (including those in North America) use a voltage
of 110V~130V, while another 120 countries (including most of Europe),
use a voltage of 220V~230V. The electricity in China is generally
220V, 50HZ, AC (Hong Kong is 200V; Taiwan is 110V).
If you travel to China and wish to bring electric devices for
use during your stay, a transformer, which can be bought in China
for 100-200 Yuan, is necessary. Most of the hotels in China have
both 110V and 220V electrical outlets in the bathrooms, though
in the main portion of the guest room, only 220V sockets are available.
As the shape of plugs also varies between countries, a portable
plug converter may also be necessary. These can be purchased from
travel stores (such as Franzus) or electronics stores (i.e. RadioShack,
Best Buy) in your local countries.