I saw the word "dongle" while reading, but what does it do? Why would you want to have one on your system?
A dongle is a piece of hardware, now usually a USB device (in the past, they also connected to serial and LPT ports), that plugs into a computer to provide copy protection for a piece of software.
Usually they come with more expensive software packages to prevent piracy because you not only have to have the software installed, but that physical device (the dongle). So even if you gave your friend a copy of the software, you only have the one physical dongle to use it, and share.
You don’t really want to have one on your system…the software maker wants it. Most consumers hate them, but they since they are mostly on high-end software, they are seen more in businesses. Strange name, annoying devices, but effective.
For more info, go here:
Dongle is essentially just a synonym for peripheral.
In the past, most dongles were connectors that plugged into the serial or parallel port to provide a means of enforcing copy-protection for expensive software (often 3D graphics packages, CAD programs, etc.) This was done because having the license enforcement code be in a piece of hardware as opposed to in a piece of software was presumed to be unhackable/uncrackable. (It was usually not very effective, and most of these programs were indeed cracked because regardless of the hardware, software entered the equation at some point, at which time the program became vulnerable—even hardware has been hacked like unlocking AMD CPUs for overclocking.)
These days, most dongles provide new functionality that is not built into the motherboard (eg Bluetooth, IRDA, etc.), or as receivers for wireless input devices. A while back, these devices would usually be somewhat bulky devices that sat on the desk, but they have since been miniaturized so that they are basically just a little plug on a USB port.
In either case, they are generally caps, containing all of their functionality, that connect to a system port and have nothing plugged into them (ie, a terminator). However, some dongles can have things plugged into them like keyloggers and audio adapters.
As you can see, the term dongle applies to adapters, receivers, transmitters, and so on. In other words, it is just a term that applies to any sort of (usually small) external hardware peripheral that connects to the system (generally, wireless devices are not considered dongles).
Bluetooth serial dongle:
Remote Wonder USB receiver:
Remote Wonder II USB receiver:
PS/2 keylogger dongle:
USB keylogger dongle:
USB audio adapter:
Dongles can also be used to give a non-Bluetooth computer Bluetooth capability. This is handy in a library setting for connecting a computer to a wireless scanner, for example. I have seen one used on an older laptop for inventory purposes.