Background information

The above charger is multi voltage: it will work with any voltage between 100 and 240 volts.
History
Like most countries in the Caribbean and North and Central America, Guyana uses American-style plugs (types A and B), which are standard throughout the region for convenience and compatibility.
Keep in mind, however, that despite using American-style plugs, Guyana's electricity does not always run at 110 volts, but sometimes at 220 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. Always 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 if you are at a location where the voltage is 220 V.
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.