What is a USB Dongle?

Many devices smaller than a pack of gum can slip into the Universal Serial Bus (USB) port of a computer. These devices are called USB dongles and add features to the computer or machine that were not built in by the manufacturer. This can include the ability to connect to wireless networks, transfer data from the computer to the dongle, and increase a system's security.

In general, a USB dongle is small enough to fit into a pocket and someone can plug it into the USB port on a computer. Sometimes they include a wire that can be plugged into another device or computer, though many of them function as stand-alone hardware. The name "dongle" comes from uncertain origins, but likely originated in terms of security hardware, and has extended in use to other devices.

A storage or memory USB dongle, also called a memory stick, provides a convenient means to pass files between computers or devices. The memory stick contains a rewritable solid-state memory chip that does not require power to retain its contents. As capacities have grown and price has dropped, these portable, plug-and-play storage drives have replaced floppy disks and even writable discs for exchanging files and archiving data.

Another type of USB dongle can add Wi-Fi® functionality to a computer to provide wireless Internet connectivity. Most desktop computers can accommodate internal Wi-Fi® cards, but some laptops and notebooks rely on external gadgets for wireless connections. The USB Wi-Fi® dongle comes in many models with the most basic model working with Operating System (OS) software to locate nearby wireless networks and access them.

A Wi-Fi® finder or scanner can also come in the form of a USB dongle, allowing a person to scan for free public networks while mobile. This device often features Light-Emitting Diodes (LEDs) that light without having to boot the laptop, indicating a wireless network has been detected. A series of LEDs can indicate signal strength, letting the user glance at the dongle and instantly see if accessibility increases or decreases. Different colored LEDs might also specify encrypted or unencrypted networks.

USB Bluetooth® dongles let a device connect to a Personal Area Network (PAN). Bluetooth® has become increasingly useful for passing data between cell phones and computers, syncing Personal Digital Assistants (PDAs) to laptops, and making hands-free mobile phone calls. Bluetooth® users can often activate and connect to a PAN with virtually no networking experience, and without the use of extra cables.

Laptop users, for example, might want to make their printer and laptop Bluetooth®-enabled. A USB Bluetooth® dongle can wirelessly link the two machines in a few seconds, allowing the user to send print jobs to the printer without having to connect the devices with a cable. Some newer printers include built-in wireless functionality, but a USB dongle may be needed for a computer or other device to connect to it.

There are also proprietary USB dongles that act as a security token to authenticate software in order to protect it from use by unauthorized persons. These types of devices can verify credentials or supply a password to a Virtual Private Network (VPN) for field personnel, for example, operating on a secured system. Without the USB security dongle and proper credentials, a person cannot log into the network or access the software under its protection. There are even devices used to access computer terminals, locking the system unless the user has connected the appropriate USB dongle to it.