Wi-Fi offers short-range wireless high-speed data connections between mobile data tools and close-by Wi-Fi access points. The area covered indoors is 30 to 100 meters and outdoors cover about 650 meters. it's a WLAN (Wireless Local Area Network) technology.
In Past Wi-Fi, 802.11g, is capable of give speeds up to 54Mbps and compatible with 802.11b (give up to 11Mbps) and current standard is called 802.11n (giving up to 150Mbps per channel).
Wi-Fi is more faster than any data technologies operating through the mobile network like GPRS, EDGE and alike UMTS and HSDPA.