An explanation of an electrical adapter may sound a bit simplistic, but it's important to know the difference between an adapter and a transformer, especially if you're going overseas and expect to use electricity to operate your personal devices like laptop computer, shaver or hair dryer. If you don't know the difference between an adapter and a transformer, you could ruin your electric device, and risk personal injury as well as fire.
To make matters worse, manufacturers often refer to their transformers as adapters. It's a misnomer that can cause confusion, so I hope to clear it up with this overview of the basics.
Electrical adapters are devices that change the physical configuration of your electric plug. This allows you to use your (male) plug where it normally wouldn't fit into the (female) outlet. An adapter will have both a male and female side. The female side is where you plug in your electric appliance. On the male side will be prongs, blades or studs so it can be plugged into the (female) wall outlet. Once you do that, electricity will flow from the wall outlet to your electric appliance.
Another type of adapter commonly used is one that plugs into the outlet and allows you to plug in multiple electrical appliances into that single adapter. It essentially turns a single outlet into many. Such adapters can allow you to convert the physical configuration as well - from three prong to two, or from polarized plugs (one blade taller than the other) to non-polarized plugs (both blades of equal height). Otherwise, they'll simply have the same configuration on both the male and female sides, and serve as an outlet multiplier.
There are adapters that serve as an outlet multiplier and allow you to plug in polarized or non-polarized two or three prong plugs, and plug into a polarized or non-polarized outlet. So, they can help you with a polarized plug that won't fit into an old fashioned non-polarized outlet. They can also serve as a simple outlet multiplier, and help you plug a three prong plug into a two prong wall outlet. I like these adapters the best because they allow me to do most anything, regardless of the configuration of my plug or outlet.
To remember the role of an adapter, just think of the typical adapter that allows you to plug a three pronged electrical plug into a two pronged outlet. The electrical adapter changes the physical configuration of your plug (or accepts multiple plugs) so you can use the plugs you have with the outlet that's available. Some adapters for use overseas come in sets so you can convert a range of plugs to fit a range of outlet styles.
So, now that the role of an adapter is clear, be careful not to simply hook things up to the power outlet unless you know there is a match between the electrical output and the power requirements of what you're trying to operate. You might need a transformer to convert the power to match the needs of your device.
