I've seen lots of ads recently touting both Wi-Fi and Bluetooth in portables. What's the difference and why do I need both?

New users are often confused by the two technologies, which have very different applications, although they share the same 2.4GHz frequency band. Wi-Fi (or 802.11a/b/g) is a medium-range standard that lets you connect to the Internet wirelessly via a home Wi-Fi router, office Wi-Fi net, or public hotspot. In each case you can operate up to about 100 feet away from the wireless base station. Wi-Fi speeds range from 11Mbps for first-generation 802.11b, to 125Mbps for the latest enhanced 802.11g equipment. At 125Mbps, real-world throughput is similar to 100Mbps wired Ethernet, a major achievement.

By contrast, Bluetooth is a personal area networking technology, operating within one room at most, and at much lower speeds (771Kbps for Bluetooth 1.x, 2.1Mbps for Bluetooth 2.0). It is designed to inexpensively connect things like keyboards, mice, headsets and printers to computers, PDAs, and cell phones, and therefore does not need broadband capability. Bluetooth does not require a router, relying on device-to-device connections, and supporting a maximum of 8 devices. Wi-Fi also allows peer-to-peer ad-hoc networking (see next question), but most connections are via routers.