The only reason you need a voltage adapter is to keep your electronic devices away from harm’s way. While with digitization the world today has come closer and is one small little global village, the truth is that there are many aspects on which the world still needs to work a lot, in terms of uniformity.
Different countries have different electrical standards. For example, the US and for that matter most of the countries in this part of the world, have electrical supplies working at 110 volts. In some, the systems operate at about 120 volts. The cycles per second in the US and nearby is about 60 Hz, whereas the countries that belong to the Eastern Hemisphere use 220 volts to 240 volts with 50 Hz cycles. Then there are certain other countries like South Africa, where the electrical supply is of the Alternate Current type.
This means that that the electrical systems in all countries are different. Nations where the electrical supply is the DC-type, electrical and electronic devices can be easily destroyed if they are plugged into sockets that are different from what they were originally manufactured for.
Using a voltage adapter helps in making the shape of the device plug compatible with that of the outlet. The adapter should be used only when you are sure that the shape of the plug is the only difference that exists between your electrical device and that of the system. Different countries have different plug shape requirements. It is good to first understand the electrical system requirements in the other country where you are planning to travel to before buying a voltage adapter. If you are a resident of the US or nearby and planning to travel to an Asian or African country, you would want to buy a 110 to 220 volt voltage adapter. Provided, the only difference in the electrical system of your home country and the other is the plug shape. Remember, that adapters do not change the voltage or any other electrical parameter per se.