Typically, the tied product may be a less desirable one that the buyer might not purchase unless required to do so, or may prefer to get from a different seller. If the seller offering the tied products has sufficient market power in the tying product, these arrangements can violate the antitrust laws.
In general, a hub refers to a hardware device that enables multiple devices or connections to be connected to a computer. An example is a USB hub, which allows multiple USB devices to be connected to one computer, even though that computer may only have a few USB connections. The picture to the right is an example of a USB hub. Note: In the Device Manager, the root hub is your computer and the first USB hub.
USB hubs are useful for plugging in multiple devices to a computer. USB hubs are especially useful with a computer that does not have many ports available internally. A variety of USB cables, which can plug into a USB hub. USB cables are used to connect devices -- such as printers, keyboards and music players -- to computers.