North America operates on 110/125 volt Alternating Current (AC). However, most of the world operates on 220/250V AC. In order to use a North American appliance abroad, it is necessary to convert (or step-down) the 220/250 volts with either a converter or transformer. Buy here.
Dual voltage/worldwide voltage appliances (i.e. 100/240V, 110/220V or 120/250V) are capable of being used on 110/120V and 220/250V and do not require a converter or transformer - all you may need is the proper adapter plug(s). If you are unsure about your appliance, always check with the appliance manufacturer.
US single volt (i.e. 110/120V) appliances operate only on 110/120 volts and require the use of a converter or a transformer when used outside the US. Buy here.
A list of international voltages operating in most countries can be found at http://www.flanagan.com.au/voltages.htm.
You should also be aware that there are differences in video standards around the world. Depending on your country, your purchase may or may not be compatible with other video equipment or broadcast video signals.