Many of your devices can be powered through your computer's USB port, but for a dedicated current, you should get an AC charger. This will make sure you phone or tablet continues to be charged even if your computer goes into hibernation. Using an AC charger will also prevent an excessive power drain on your laptops battery. AC chargers can also be designed to charge a specific battery type, which will allow you to charge a battery while you continue to use your phone. Units are available for US and European style outlets, and many come with an adapter to be used with both.