That depends on your home country. France uses the same plug as most of Europe, except the UK and Ireland. You will need plug C, E, or F. This is the rounded two prong plug.
The voltage is 230 but most electronics can handle different voltages (120 in the US) with just the plug adaptor. That's what that black brick on you power cord does.
If you have other electrical items, such as a blow dryer or razor, there will be an American-style socket on the wall of most hotel bathrooms.
Any good luggage store can help you before you leave, but the prices are better at hardware stores. about 6 years ago