A USB decoration is a device that uses the Universal Serial Bus (USB) protocol on a computer or other host, and is primarily a decorative device (using the USB port for power).

Decorative computer peripherals have been around for a long time, however USB decorations are the most prominently used today. This is most likely because of the popularity of USB and the ability for them to work on most modern computers.

Most USB decorations do not use the communications features of the USB bus. This can cause many problems, especially if the device is rewiring the full 500mA of power available. The usual power consumption is only 100mA, which will not impact the computer's PSU if suddenly connected, without it identifying itself first.

Often, a single USB hub is used for many decorations. While possible, the current limit on USB hubs that do not have an external power connection is 400mA. Due to the fact the default amount of power available for a device is 100mA, it is therefore only possible to run four low-power decorations. It is not possible to run a high-power decoration from a USB hub without an external power connection.

USB decorations may have no useful functionality other than aesthetic ornamentation. For example, miniature disco balls,^[1] aquariums,^[2] and pole dancers^[3] that connect to a USB port are all USB decorations.

There are many USB-based decorations in existing products—keyboards with impractical backlighting (such as ones that only turn on while pressing a key, and ones that flash to the beat of a song), mice that (when the computer is turned off) turn on/off their laser to a pre-programmed beat, or printers that show random quotes on LCD screens when not in use.

It is not uncommon for a USB decoration to have a non-passive and practical purpose. Nightlights, typing speedometers,^[3] a beverage chiller,^[4] and nodding dogs that guard internet connections^[5] are all examples of USB semi-decorations. Flash drives may similarly be themed for aesthetic value.

Although these are not pure USB decorations, they are still decorative. Usually these types of devices are simpler; all of the power can be used for the main function, not for the decoration.