 Wi-Fi is a branded standard for wireless connecting electronic devices.  A Wi-Fi device, such as a personal computer, video game console, Smartphone, or digital audio layer can connect to internet via a wireless network access point.  “Wi-Fi” is a trademark of the Wi-Fi Alliance and the brand name for the product using the IEEE family standards.  Wi-Fi uses by over 700 million people, there are over 4 million hotspots around the world and about 800 million new devices every year.

 The term Wi-FI suggests Wireless Fidelity, resembling the longest established audio- equipment classification term fidelity or Hi-Fi.  The Wi-Fi Alliance initially used an advertisement slogan for Wi-Fi, “The Standard for Wireless Fidelity”, but later removed the phrase from their marketing.  The Wi-Fi logo indicates the certification of the product for interoperability.  Non Wi-Fi technologies intended for fixed points such as Motorola Canopy are usually described as fixed wireless.

 A Wi-Fi enabled device such as a personal computer, video game console, Smartphone, or digital audio layer can connect to Internet when within the range of a wireless network connected to the Internet.  In addition to private use in homes and offices, Wi-Fi can provide public access at Wi-Fi hotspots provided either free of charge or to subscribe to various commercial services.

 Routers that incorporate a digital subscriber line modem or a cable modem and a Wi-Fi access point, often set up in homes and other premises, can provide Internet access and internetworking to all devices connected to them.  Wi-Fi also allows communication directly from one computer to another without the involvement of access point. This is called ad hoc mode of Wi-Fi transmission.  Wi-Fi technology has been used in wireless mesh networks in London, UK.

 Wi-Fi networks have limited range. A typical wireless router using b or g with a stock antenna might have a range of 32m(120ft.) indoors and 95(300ft.) outdoors.  Wi-Fi in the 2.4GHz frequency block has slightly better range than Wi-Fi in the 5GHz frequency block.  Due to the complex of radio propagation at typical Wi-Fi frequencies, particularly the effects of signal reflection of trees and buildings, algorithms can only approximately predict Wi-Fi signal strength for any given area in relation to a transmitter. This effects does not apply equally to a long range Wi- Fi, since longer links typically operates from towers that broadcast above the surrounding foliage.

 A small percentage of WiFi users have reported adverse health issues after repeat exposure and use of WiFI, though there has been no publication of any effects being observable in double-blinded studies.  Reported symptoms, purportedly caused by electromagnetic hypersensitivity to Wi-Fi, include “ headaches, dizziness, insomnia, and even erratic speeding heart beats”.

 A few health experts conclude there is a strong neurological component to described health issues.  In a BBC article, the World Health Organization says “there is no risk from low level long term exposure to Wi-Fi networks ” and the United Kingdom’s Health Protection Agency reports that exposure to Wi-Fi for a year results in “same amount of radiation from a 20min. mobile phone call. ”

 Wi-Fi allows cheaper deployment of local area network(LANs).  Manufacturers are building wireless networks adapters into most laptops.  Different competitive brands of access points and client network-interface can inter-operate at a basic level of service.  Wi-Fi operates in more than 220,000 public hotspots and in tens of millions of homes and corporate and university campuses worldwide.

 A Wi-Fi signal occupies five channels in the 2.4GHz band; and two channels whose channel number differ by five or more, such as 2 and 7, do not overlap.  The Internet protocol was designed for a wired network in which packet loss due to noise is very rare and packets are lost almost exclusively due to congestion. On a wireless network, noise is very common. This difference causes TCP to greatly slow or break transmission when noise is significant, even when most packets are still arriving correctly.

 To connect to a Wi-Fi LAN, a computer has to be equipped with a wireless network interface controller.  The combination of computer and interface controller is called a station. Each station is constantly tuned in on channel, so each transmission is noticed.  A carrier wave is used to transmit the data in packets, referred to as Ethernet frames.

As of 2010 Wi-Fi technology has spread widely within business and individual sites. Wi-Fi enables wireless voice- applications. Over the years, Wi-Fi implementations have moved towards “thin” access points, with more of the network intelligence housed in a centralized network appliance, relegating individual access points to the role of “dumb” transceivers. Outdoor applications may use mesh topologies.