A phantom load is any appliance or device that consumes power even when it is not actively being used or is in the 'off' mode. Examples of phantom loads include appliances with electronic clocks or timers, with remote controls, and with wall cubes (a small box that plugs into an AC outlet to power appliances).
Although these appliances, or 'power vampires', appear to be off, they continue to draw electricity from outlets to keep their circuits instantly ready for the next time they are turned on. Power vampires only consume a few watts when not in use, but throughout a day and over an entire year, a few watts can add up to almost 20% of a home's power.
To prevent power vampires from drawing phantom loads and raising your electric bill, any devices that are not in use and don't require power should be unplugged. Common power vampires include rechargeable battery chargers (for laptop, phone, music player, etc.), TVs, DVD players and VCRs, cable boxes and modems, answering machines, fax machines, and printers. In general, any device that has a power adapter, or "power brick," or feels warm after it has been switched off for a while is a power vampire. Using inexpensive power strips that can be shut off when devices are not in use can also prevent phantom loads.