The folks at the Costa Rica Star did a nice write up on WiFi…
Wi-Fi is also an acronym for Wireless Fidelity, although we now use Wi-Fi as if were a noun. Wi-Fi, itself, refers to the IEEE 802.11 standard. IEEE is the Institute of Electrical and Electronic Engineers, and they number their standards. The goal of standards is to provide interoperability between devices. Unfortunately, manufactures interpreted the standard differently. In 1999, a group of industry leaders formed the Wi-Fi Allianceto certify products that complied to the IEEE 802.11 standard. The standard contains a number of subsections that are identified by appending lower cases letters to the standard.