The US uses types A and B electrical outlets with a standardized voltage of 120 V and frequency of 50 Hz. An adaptor (which changes the physical plug) and/or converter (which changes the electric current) are necessary if you plan to use an appliance with voltage different from the standard within the country you are visiting.
Universal Power: 'INPUT: 100-240V, 50/60 Hz'
Check your electronics to see if they have a label of 'INPUT: 100-240V, 50/60 Hz' -- this is often found on tablet/laptop chargers, cameras, cell phones, and toothbrushes. In these instances, all you will need to bring is a power plug adapter.
If your appliance has dual voltage you will still need an adaptor for the plug if your destination country uses a different type.
When packing your electronic items for travel, please review the converter electric current level to make sure it is the same or greater than the items you are planning on using. If you plan on utilizing or transporting a sleep apnea machine, please remember to pack an extension cord and adapter plug to ensure proper function.