Wi-Fi is the common name for wireless local area networking based on the IEEE 802.11 family of standards. It lets devices exchange data over radio instead of cabling, joining a network through an access point or directly with one another. The technology is now so pervasive that the brand name “Wi-Fi” is often used as if it were the technology itself, but underneath it is a specific set of IEEE standards that define how the radios share the air and how frames are formatted and delivered.
The foundational document is IEEE Std 802.11-1997, the “IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” approved in 1997. It defined a single MAC layer paired with three alternative physical layers: a diffuse infrared option and two radio options in the 2.4 GHz band, one using frequency-hopping spread spectrum and the other using direct-sequence spread spectrum. The original standard supported net data rates of just 1 and 2 megabits per second, modest by later standards but enough to prove the architecture. The 1997 standard was revised in 1999, and that revision is now the baseline that later amendments built upon.
The 802.11 MAC uses a carrier-sense, collision-avoidance scheme suited to a shared radio medium, since unlike wired Ethernet a station generally cannot detect a collision while transmitting. This places 802.11 in the same data-link role that Ethernet plays on the wire, so a wireless device can run the ordinary internet protocol stack on top of it. In the layered model, 802.11 occupies the physical and data-link layers, and TCP/IP rides on top unchanged.
Raw speed climbed quickly through lettered amendments. 802.11b in 1999 reached 11 Mbit/s in the 2.4 GHz band and drove the first wave of mass adoption; 802.11a used the 5 GHz band; 802.11g, 802.11n, 802.11ac, and 802.11ax pushed rates into the hundreds and then thousands of megabits per second while adding techniques like multiple antennas and wider channels.
The consumer-facing “Wi-Fi” brand comes not from IEEE but from the Wi-Fi Alliance, an industry group that certifies that products from different vendors actually interoperate. Because the IEEE standard leaves room for implementation differences, the Alliance’s certification program and its marketing name gave buyers a simple guarantee that a “Wi-Fi Certified” device would work with others. That combination, an open IEEE standard plus a trusted interoperability brand, is a large part of why wireless networking spread so fast into homes, offices, and public spaces.