ALWAYS check the style and voltage of the electrical outlets for the location that you will be visiting.
WorldStandards.eu provides pictures and a listing of the different types of plugs and adapters that you may need.
MOST appliances nowadays will work with any of the voltages (that's partly what that giant box that comes with your laptop charger is for), but ALWAYS check the voltage of the appliance you are trying to charge or use. I've only actually had an issue with this once - I was trying to charge a portable battery pack, using a usb charger plugged into a North American style plug, in turn plugged into a European style plug, and that particular battery pack is now a paper weight after it sparked and blew the breaker on the electrical panel. Luckily it didn't catch fire.