Wireless isn't just for Internet and computer-to-computer connectivity?it can also be used to move data between your Mac and your peripherals. This is where Bluetooth comes in. Bluetooth is a short-range, relatively low-speed wireless technology with an operating range of approximately 30 feet (10 meters) and a maximum transmission rate of only 1 Mbps.
If you think of Wi-Fi as Ethernet without wires, the comparable way to think of Bluetooth is USB without wires (though we're talking about the slower USB 1.0 standard used in most peripherals; USB 2.0 is quite zippy). For instance, hooking up a PDA used to require a USB-attached cradle, but you can now transfer data wirelessly between your Mac and Palm via Bluetooth.
A word of advice: the Bluetooth technology and its implementation on the Macintosh is a work in progress. Early press about Bluetooth raved about how it could be used to hook up printers, keyboards, and mice. Unfortunately, Apple's Bluetooth support is tweaky at best; we've found that Bluetooth tends to be flaky, and sometimes it just fails to work at all.
Bluetooth is a pretty weird name, if you think about it; unlike, say, Wi-Fi, Bluetooth doesn't have that high-tech ring. That's because the Bluetooth technology was named in honor of a real person, the Danish King Harald Blåtand, who ruled approximately from A.D. 960 to 985, and who is reported to have brought Christianity to Scandinavia and united Denmark and Norway. "Bluetooth" was a nickname that had nothing to do with blue teeth: it referred to the king's dark complexion, which was unusual for a Viking.