As computers merge into entertainment systems, you're apt to sit farther and farther away from the display screen. A home entertainment computer, for example, fits into your living room more like a television set, at one end of the room with you at the other. Just as a wireless remote control has become de rigueur for your television, a wireless keyboard gives you the same flexibility when the computer takes over.
Wireless keyboards are two-piece systems. Each involves the keyboard itself, which functions as a transmitter, and a base station, which acts as the receiver. (Keyboard communications are actually a two-way street, but the transmitter/receiver distinction is valid as a view of the data you generate by typing.) A single base station can serve both a wireless keyboard and wireless mouse (or other pointing device).
The first wireless keyboards used infrared technology (similar to, but predating, IrDA), with the interface (a little red optical sensor) built in to the host computer. Today, however, wireless systems are add-ons that plug into conventional interfaces—either the keyboard port or USB port. The connection between the base station and your computer is completely conventional. Your computer receives exactly the same scan codes or USB packets it would expect from a plug-in keyboard.
All the magic is in the wireless link. And wireless links might as well be magic because they need to follow no standards other than the Federal Communications Commission's limits on unlicensed radiation. That is, as long as they don't use too much power—definitely less than what is apt to cause interference—and stick to the authorized frequency bands, wireless keyboard-makers are free to do whatever they want with their signals.
The range of these wireless systems stretch from about 5 feet to more than 30 feet. Unfortunately, the only guidance available as to the range of a particular keyboard is the claim of its manufacturer.