What kind of power outlets are used in Vietnam?  

Good question CaraA! From my Google search this is what Google says:

'For Vietnam there are three associated plug types, types A, C and F. Plug type A is the plug which has two flat parallel pins, plug type C is the plug with two round pins and plug type F has two round pins with two earth clips on the side. Vietnam operates on a 220V supply voltage and 50Hz.'

You'll see some places using the standard A plug, which is what the US and many other countries use. As well, Type C and F are essentially Euro plugins, so those will need an adapter to use if you have a type A connection. 

Adapters are cheap and reliable. I would also consider getting a voltage converter just in case. Some devices may not work properly on a Vietnamese connection. 

I have never thought of this! I didn't know that some countries uses different kinds of power outlets! I will have to check for sure as well next time I travel to a different country.