Voltage, frequency, and plug type are often different in other parts of the world. Physical compatibility of receptacles does not guarantee voltage, frequency, or connection to earth (ground) compatibility, including plugs and cords. Older standards may still exist in some regions. For this reason, it is important to be aware of the differences, particularly if your product relies on electricity.

List of Voltages & Frequencies (Hz) Around the World
The website Generator Source provides a comprehensive chart which includes information on voltages and frequencies around the world.

Country-by-country list of plugs, sockets and voltages
The Worl Standards website provides a full overview of all countries of the world and their respective plugs/outlets and voltages/frequencies used for domestic appliances. The table shows that in most countries the mains supply is between 220 and 240 volts (50 or 60 Hz); countries that operate on 100-127 volts are greatly outnumbered. The list also reveals that types A and C are the most frequently used electric plugs worldwide.

Mains electricity by country
Wikipedia’s page on Mains electricity by country includes a list of countries and territories, with the plugs, voltages and frequencies they commonly use for providing electrical power to low voltage appliances, equipment, and lighting typically found in homes and offices.