Wi-fi is a wireless Wireless Local Area Network (WLAN) system. It use for transfer data from one a short distance. It is high-speed data-transferring method.
The older version of Wi-fi is 802.11g. Which is capable to transfer data up to 54Mbps.
At present we are using 802.11n which capable to transfer data up to 150Mbps in every channel and 600Mbps in total.