It seems nearly every electronic gadget manufactured today makes use of the ever-handy USB port. Early computers featuring USB normally had only one or two ports located inconveniently at the back of the case. Newer computers feature several built-in USB ports, and many cases now place two or more of these ports in front. Even so, additional ports are often needed, and having them conveniently accessible makes all the difference. The USB hub does just that.

A USB hub is a small, light unit with multiple ports for plugging in USB devices. It is commonly connected to a USB port located on the back of a desktop computer by using an extension cable. Once the hub is plugged in, you can set it wherever is convenient, avoiding the hassle of accessing the rear of the system. A USB hub is also great for laptops with only one or two ports. Most hubs can support up to 127 devices.

A self-powered USB hub can be used to connect digital cameras, card readers, keyboards, mice, MP3 players, memory sticks and many other handheld USB devices. For more robust components such as external drives, printers, scanners or fax machines, an AC-powered USB hub is a better choice. Some of the AC-powered hubs come with an AC-adapter, while others have the capability, but require the separate purchase of an adapter. When shopping for a USB hub, be sure to get one that will best meet your needs.

Another feature to look for is 1.1 or 2.0 compliancy. This refers to the two versions of USB technology. USB 1.1 is capable of data transfer speeds up to 12 megabits per second (mbps), while USB 2.0 can transfer data at 480 mbps, 40x faster. Initial USB devices were engineered to use USB 1.1, while later devices took advantage of the newer 2.0 compliancy.

A USB hub that supports 2.0 is often backwards compatible, supporting 1.1 devices as well. The hub automatically detects and runs at the fastest rate the device will support. A USB hub that supports 2.0 cannot "push" a 1.1 device to run faster than its design. Conversely, a hub that only supports 1.1 may or may not support a 2.0 device, but if it does, it will slow it down to 12 mbps —- the fastest speed the hub supports.

Virtually all USB devices are plug 'n' play, or hot-swappable, but it's wise to be conservative with this feature when using an external hard drive with a USB port. Data could be lost due to software bugs or if the drive is unplugged while busy.

A USB hub is an inexpensive, handy addition to any system, especially useful with laptops that normally have too few native USB ports and older systems that have rear ports. A USB hub can be purchased in a four-port model, a seven-port model, or greater. Multiple hubs can be used for scalable growth.