Unlike many other wireless standards, 802.11 runs on "free" portions of the radio spectrum. This means that (unlike cell telephone communications) no license is required to broadcast or communicate using 802.11 (or Wi-Fi).
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.
A recent addition to the Wi-Fi standard is the Wi-Fi Protected Access solution (WPA).
Together, the physical and access control layers, along with extensions intended to implement extra features (such as WAP for security) make up the 802.11 Wi-Fi standard.

Using Wi-Fi

If you've picked up this article, you probably have a use in mind for Wi-Fi. More precisely, you have a use in mind for a device that uses the Wi-Fi standard to broadcast and receive information.
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 article, 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 article 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 article to learn how to create a wireless network.

Understanding Wi-Fi Networks

You're on the road and you've found a location with a Wi-Fi broadcast device that your mobile computer can talk to. A Wi-Fi broadcast device is variously referred to as an access point, an AP, or a hotspot.
With your access point located, you're ready to sit right down, establish a wireless connection, and start reading your email and surfing the Web, right? Not so fast, partner.
It's really important to understand that being able to "talk" with a wireless access point just means that you can "talk" with a wireless access point. It doesn't mean that you can connect to the Internet unless the wireless access point is itself connected to the Internet.
So if Starbucks or whoever wants to provide you with the chance to surf on their turf while you sip that latte, Starbucks needs to provide an Internet connection. Generally, this connection is wired, and uses a cable or DSL (digital subscriber line) telephone line for high speeds.
A high-speed wire brings the Internet to the location, and a Wi-Fi access point broadcasts the wireless Internet connectivity to wireless devices (in technogeek-speak, the wireless devices are generically referred to as clients).
Between the Internet connection and the Wi-Fi access point, there also needs to be some hardware designed to connect with the Internet and share the connectivity. There are a whole lot of different ways this can be done, depending on many factors. For example, is a wired network also involved?
For now, you need to understand that connecting to the Internet via Wi-Fi involves four things:

• Your Wi-Fi device (the client)
• A Wi-Fi broadcast unit (the access point)
• Network connectivity hardware (such as a router and modem)
• The actual Internet connection (usually via cable or DSL)

Using Wi-Fi on the Road

For now, I'd like to go over some basics related to using Wi-Fi on the road.
For starters, as I explained in the preceding section, "Understanding Wi-Fi Networks," it's not enough to find a Wi-Fi wireless access point. Behind the scenes, the wireless access points need to be capable of providing access to the Internet, usually via a high-speed cable or DSL connection.Connecting

With your Wi-Fi device happily chugging and ready to go, a good strong signal from a Wi-Fi access point broadcasting its way to you, and a behind-the-scenes Internet connection that the access point is plugged into, what's next?
Connecting to a public Wi-Fi access point is generally really easy. Usually all you have to do is open your Web browser. In some cases any Web browser will do, but often you need to use Microsoft's Internet Explorer. Paying for It

There are two sides to Wi-Fi. One is the grass-roots peoples' movement in which propeller-headed persons (such as the author of this article) put up free Wi-Fi access points that can be used by anyone within range for free. (Of course, in my case the range is about 50 feet from my house in a quiet residential neighborhood, so it may help a neighbor or two, but is unlikely to be of much use to anyone else.)
As a practical matter, you are far more likely to encounter the other side of Wi-Fi, which goes like this: Wi-Fi is one of the few areas in technology that has really boomed since the technology bubble burst in 2000. So let's try to build out a public infrastructure so that everyone can use Wi-Fi and charge whatever the market will bear.
The capitalistic, entrepreneurial side of Wi-Fi is what you may meet when you access the Internet via Wi-Fi in public venues such as Starbucks, Borders, hotels, and airports. There will be no free lunches in these venues! On the other hand, some businesses have found that offering free Wi-Fi is a great way to entice customers to stick around for a while and spend more money. In addition, there is a hard-core contingent of idealistic engineering types who see offering free Wi-Fi access as a worthy endeavor. So perhaps sometimes there are free lunches! And when there are, they are really tasty!
Typically, you pay for your access based on how long you use it either with a payment plan, or as you go. If you plan to pay as you go, you'll need to have a credit card handy when you log on to the Wi-Fi network.Finding Access Points

Where are the public Wi-Fi access points? Why, everywhere and nowhere, like a taxicab on a rainy day.
Actually, the picture is not nearly so bleak, and there are more and more wireless access points every day.
There are also a great number of online tools that help you find access points that meet your needs.

The Free Spectrums

As you probably know, any signal that is sent without wires is called a radio transmission. A common example is that the radio in your car receives transmissions. Similarly, a standard cell phone works by receiving—and transmitting—radio signals.
Every device that broadcasts a radio transmission does so at a particular frequency, which is the oscillations, or movement from peak to trough, of the electromagnetic wave created by the transmission.
The entire set of radio frequencies is known as the radio spectrum. Contiguous portions of the radio spectrum are called bands, as in "the FM band."
Radio frequencies describe the oscillations of a radio wave. For example, if you are tuned to an FM radio station at 92.5, it means that the radio transmission is oscillating at 92.5 megahertz per second. 92.5 megahertz (pronounced "may-ga-hurts" and abbreviated MHz) means that the radio transmission wave oscillates, or moves from its valley to its peak, at a rate of 92,500,000 times per second. If you think of this as listening from a distance to a really rapidly vibrating tuning fork, you have the right picture.
The AM radio spectrum was developed before the FM spectrum, so it is lower down the spectrum, ranging from 535 kilohertz to 1.7 megahertz, or 535,000 to 1,700,000 oscillations per second. For example, 720 on the AM dial means that your radio receiver is tuned to a frequency of 720,000 oscillations per second.
There are frequencies above, or higher than, the FM frequency as well as below it. In fact, as I'll explain in a moment, Wi-Fi transmissions run at some of these higher frequencies.
One thousand megahertz is equal to one gigahertz (pronounced "gig-a-hurts" and abbreviated GHz). So when you refer to the 2.4GHz frequency, you are actually talking about 2,400,000,000 (2.4 billion) oscillations per second.
There are only so many frequencies in the radio spectrum that can be used for transmissions. This has inevitably led to the potential for conflicts about usage, as well as attempts to dominate particular frequencies.Although it is commonly referred to as the 2.4GHz band, the actual spectrum is 2.39GHz–2.417GHz. In the case of the 5GHz spectrum band, the band actually runs from 5.47GHz to 5.725GHz.