THE WI-FI ALLIANCE The Wi-Fi Alliance is a not-for-profit organization that certifies the interoperability of wireless devices built around the 802.11 standard. The goals of the Wi-Fi Alliance are to promote interoperability of devices based on 802.11, and, presumably, to promote and enhance the standard. For better or worse, this is no neutral organization. The members of the Wi-Fi Alliance are manufacturers that build 802.11 devices. As of this writing, there are 205 companies that belong to the Wi-Fi Alliance and more than 900 products that have been certified as Wi-Fi interoperable. The promise that the Wi-Fi Alliance makes is that if you buy an 802.11 device with the Wi-Fi seal of certification, the device will work seamlessly with any other Wi-Fi certified device. You can find more information about the Wi-Fi Alliance at the Alliance's Web site, www.wi-fi.org.

WHAT IS A STANDARD? The words standard and protocol are essentially synonymous (protocol is a slightly more technical term). When used in its engineering context, a standard means the technical form of something such as a message or a communication. In other words, a standard might specify how the communication is made. If you know the standard, you know how to decode the message. In order to work with a standard (called complying with a standard), a device needs to know both how to encode into the standard and decode from the standard. A standard for working with communications, such as the Wi-Fi standard, will generally involve specifications both at the hardware and the software level (in geek-speak, these levels are called layers). You can think of the standard as a kind of secret handshake that gets you into a club. If you (or your wireless device) know how the secret handshake works, you can find out what the other people in the club (the other wireless devices) are actually saying.

But Wi-Fi has garnered a huge amount of attention from people who would normally be unconcerned about engineering details: in other words, normal human beings like you and me. Students, professionals, homemakers, English Lit majors, and office workers are all talking about Wi-Fi.

The really big question is: Why is Wi-Fi getting all this attention? I'll get to that soon. I'll also show you how Wi-Fi can change your life (for real!). But first I'd like to tell you a little bit more about what Wi-Fi is.

Wireless Spectrums

The free portions of the radio spectrum used by 802.11 (and Wi-Fi) are the 2.4GHz band, and, more recently, the 5GHz band. As you may know, many household appliances such as microwave ovens and (most significantly) wireless telephone handsets also use these free spectrums.

With a wireless telephone handset, a base station is connected to the telephone line, and the handset communicates with the base station over the "free" radio frequency, so that you can roam about your home or office while talking on the phone. Clearly, these wireless telephone handsets are not the same thing as cell phones, which do not connect to a telephone wire at all and use licensed portions of the spectrum.

Using Wi-Fi

The two most common uses for these devices both involve freedom:

• You can work almost anywhere by using a mobile Wi-Fi device to connect to the Internet without wires when away from your home or office.

• You can free yourself from the need to drill holes and snake wires by creating a network at the home or office using Wi-Fi devices.

In this chapter, I'll give you a picture of the hundred-mile view of each of these important uses for Wi-Fi devices. Your perspective is going to be pretty different if you've bought this book to learn how best to take your laptop on the road (or what kind of mobile device to buy) than if you've bought this book to learn how to create a wireless network.