Short for "Wireless Fidelity." Wi-Fi refers to wireless networking technology that allows computers and other devices to communicate over a wireless signal. It describes all network components that are based on one of the 802.11 standards, including 802.11a,802.11b, 802.11g, and 802.11n. These standards were developed by the IEEE and adopted by the Wi-Fi Alliance, which trademarked the name "Wi-Fi".
Wi-Fi is the standard way computers connect to wireless networks. Nearly all computers now have built-in Wi-Fi cards that allows users to search for and connect to wireless routers. Many mobile devices, video game systems, and other standalone devices also include Wi-Fi capability, enabling them to connect to wireless networks as well. These devices may be able to connect to the Internet using a Wi-Fi signal. However, it is important to understand that the Wi-Fi connection only exists between the device and the router. Most routers are connected to a DSL or cable modem, which provides Internet access to all connected devices.
Since Wi-Fi is a wireless networking standard, any device with a "Wi-Fi Certified" wireless card should be recognized by any "Wi-Fi Certified" access point, and vice-versa. However, wireless routers can be configured to only work with a specific 802.11 standard, which may prevent older equipment from communicating with the router. For example, some 802.11n routers can either be configured to only work with 802.11n devices. If this option is chosen, 802.11g devices will not be able to connect to the router, even though they are Wi-Fi certified.
How It Works :
A wireless network uses radio waves, just like cell phones, televisions and radios do. In fact, communication across a wireless network is two-way radio. Here's what happens:
1. A computer's wireless adapter translates data into a radio signal and transmits it using an antenna.
2. A wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired ethernet connection.
The process also works in reverse, with the router receiving information from the internet, translating it into a radio signal and sending it to the computer's wireless adapter. The radios used for Wi-Fi communication are very similar to the radios used for walkie-talkies, cell phones and other devices. They can transmit and receive radio waves, and they can convert 1s and 0s into radio waves and convert the radio waves back into 1s and 0s. But Wi-Fi radios have a few notable differences from other radios:
● They transmit at frequencies of 2.4 GHz. This frequency is considerably higher than the frequencies used for cell phones, walkie-talkies and televisions. The higher frequency allows the signal to carry more data.
● They use 802.11 networking standards, which come in several flavours:
802.11b is the slowest and least expensive standard. For a while, its cost made it popular, but now it's becoming less common as faster standards become less expensive. It can handle up to 11 megabits of data per second.
802.11g transmits like 802.11b, but it's a lot faster , it can handle up to 54 megabits of data per second.
802.11n is the newest standard that is becoming widely available, although it's not widely used yet in access point hotspots. It promises still faster speeds.
Advantages
Wi-Fi allows cheaper deployment of local area networks (LANs). Also spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.
Manufacturers are building wireless network adapters into most laptops. The price of chipsets for Wi-Fi continues to drop, making it an economical networking option included in even more devices.
Different competitive brands of access points and client network-interfaces can inter-operate at a basic level of service. Products designated as "Wi-Fi Certified" by the Wi-Fi Alliance are backwards compatible. Unlike mobile phones, any standard Wi-Fi device will work anywhere in the world.
Wi-Fi operates in more than 220,000 public hotspots and in tens of millions of homes and corporate and university campuses worldwide.The current version of Wi-Fi Protected Access encryption (WPA2) as of 2010 is widely considered secure, provided users employ a strong passphrase. New protocols for quality-of-service (WMM) make Wi-Fi more suitable for latency-sensitive applications (such as voice and video); and power saving mechanisms (WMM Power Save) improve battery operation.
Reference: http://en.wikipedia.org/wiki/Wi-Fi
Reference: http://www.wisegeek.com/what-is-wifi.
Reference:http://computer.howstuffworks.com/wireless-network1.htm
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