802.11, referred to in full as IEEE 802.11, is a set of standards created by the Institute of Electrical and Electronics Engineers LAN/MAN Standards Committee (IEEE 802) to govern wireless networking transmission methods. It was developed for computer communication in wireless local area networks (WLAN) in the 5 GHz and 2.4 GHz public spectrum bands.

The term "802.11" may often be considered synonymous to "wireless fidelity" or "Wi-Fi," but the Wi-Fi Alliance has determined that the two terms describe slightly different sets of overlapping standards. 802.11 specified two raw data rates of 1 and 2 Mbps, transmitted through infrared (IR) signals (which is still part of the standard but is without actual implementations), frequency hopping or direct-sequence spread spectrum in the Industrial Scientific Medical frequency band at 2.4 GHz.

802.11 encompasses a family of amendments (named by suffixing a letter of the alphabet, e.g. 802.11a, 802.11b, 802.11c, etc.), each a revision of the one preceding it. Its most popular protocols are 802.11b and 802.11g, which both use the 2.4 GHz band, sometimes making them prone to interference from microwave ovens and cordless telephones. The first wireless networking standard is 802.11a, which uses a 5 GHz band; however, 802.11b was the first widely accepted one.

The first standard was actually known as "legacy mode," which specified Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) as its medium access method. However, 802.11 legacy mode it was considered more of a beta standard than an actual standard.

802.11n is a new amendment that is still under draft development. It features a new multi-streaming modulation technique, and products based on its pre-draft versions are already available on the market.

Other 802.11 amendments (c-f, h, j) are extensions or corrections to previous amendments. All 802.11 amendments are wireless modulation techniques that use the same basic protocol.

Original versions of 802.11 featured weak security to conform to some governments’ export requirements. The weaknesses in the 802.11 Wired Equivalent Privacy (WEP) security mechanism were brought to attention by a research paper from a group in the University of California, Berkeley.

Due to these security flaws, it was possible to intercept transmissions and gain unauthorized access to wireless networks. The 802.11i (also known as WPA2) amendment, developed by an IEEE task group and ratified in June 2004, featured an enhancement in security following government and legislative changes. Instead of RC4, which was the encryption standard for WEP, 802.11i uses government-strength encryption in Advanced Encryption Standard (AES). WPA2 (AES PreShared Key) is the recommended encryption for modern consumers.