Wireless networking, or Wi-Fi, is a runaway success. The grassroots movement has soared to 18 million users, up from 2.5 million in 2000. Now, the technology is quickly moving into the mainstream. Here's why it has caught on:Wi-Fi-Ready Devices

Dell (DELL

), Toshiba (TOSBF

), and TiVo (TIVO

) are building Wi-Fi into computers and digital recording devices. Over 90% of new laptops will be Wi-Fi-ready by 2005, up from 35% by yearend 2003.Nationwide Network Bets

At least four commercial Wi-Fi networks are in operation or under development in the U.S. they include Voicestream, Toshiba, Boingo, and Cometa Networks, which is backed by IBM (IBM

), Intel (INTC

), and AT&T (T

). That will raise awareness and push prices lower.Broadband Lift-Off

Wi-Fi is getting a boost from the popularity of broadband, which is growing 30% this year. That's because Wi-Fi is an inexpensive way to connect several household computers to a single high-speed internet connection.Tech Titans Jump In

Intel, Microsoft (MSFT

), Cisco (CSCO

), and IBM are pushing Wi-Fi just as hard as pioneers like Boingo are. In March, Cisco bought Wi-Fi gearmaker Linksys Group for $500 million. And Intel is spending $300 million to promote its Centrino Wi-Fi chips.Rampant Innovation

Wi-Fi technology is advancing fast. Intel and MeshNetworks are developing antennas that can reach for miles instead of today's 300 feet. Next: Wi-Fi-ready cell phones, PDAs, and hot spots on trains and buses.Falling Prices

The price of Wi-Fi equipment is dropping. An antenna for a laptop now costs $46, down from $189 in 1999. Lower prices are opening the market to a broader group of buyers.Grassroots Phenom

Pioneers in Portland, Ore., New York, Barcelona, and Sydney continue to expand community networks in parks, bars, and coffee shops. There are now 5,000 of these free networks worldwide.

Data: In-Stat/MDR, IDC, Yankee Group, Wireless Node Database Project