Take a moment to look around you. Unless you are outside, you should see walls and ceilings decked out in technological artifacts: lighting fixtures, jacks (telephone and data), power outlets, and so forth. They are so common they’ve become a part o f the landscape. Now an invisible artifact is joining this landscape. It provides high-speed, low-cost, low-power, wireless access to the Internet and other networks over a short range. It is Wi-Fi, which is a marketing term that has grown to encompass technology built upon the three latest 802.11 Physical Layer specifications: 802.1 la, 802.1 lb and 802.1 lg.