Background information
History

An American-style socket alongside a British-style power outlet
The official wall outlet in Saint Vincent and the Grenadines is the British type G, which can be found in all households and hotels. Because American-style type A and B sockets are standard in the neighbouring countries and throughout the region, they are also commonly installed in most homes and hotels for convenience and compatibility, but they are not available in all places.
Keep in mind that even when you use an American-style socket, the electricity in Saint Vincent and the Grenadines does not run at 120 volts, but at 230 volts (except for the island of Petit Saint Vincent, which has 110 volts). This is why tourists from North and Central America - where the voltage is 120 volts - have to be sure that their appliances can deal with the electricity coming out of the socket. That is why you need to check your device's voltage listing. "INPUT: 100-240 V" means that your device is multi-voltage and that it will work with any voltage between 100 V and 240 V. Luckily, many travel gadgets (such as laptops or phone chargers) are multi or dual voltage, so most tourists will not have a problem. If your device is single voltage (e.g. "INPUT: 120V"), you will need a transformer to step down the voltage.
Click here for a global map showing the spread of the different plug types used around the world.
Click here for a detailed list of the countries of the world with their respective plug and outlet types, voltage and frequency.