Wi-Fi is the trademark of Wi-Fi Alliance covering the functionality defined by the set of IEEE 802.11 standards. This set of standards defines so-called Wireless Local Area Network (WLAN) operation principles. This name comes from the idea that Wi-Fi should provide LAN-like functionality over the air. It concerns frequency bands used, possible supported data rates, data and management frame formats etc.
Wi-Fi is now the most popular technology for providing the wireless connectivity between devices, used by over 700 million people. It allows for direct connection between two devices, but the most important use case is now to provide the wireless connection to Internet.
Used primarily by laptops in the beginning, it is becoming increasingly popular on embedded devices. One can hardly imagine now a smartphone or a tablet without Wi-Fi. It is also implemented in modern TVs and set-top boxes. Being a crucial feature for certain types of embedded devices, Wi-Fi brings the challenge of significant power consumption increase for those. Please refer to the following presentation done at ELC-E 2011 for more details on this issue: Saving power with Wi-Fi.