802.11 - The first 802.11 standard (often referred to as 802.11 Prime), initially published in 1997 by the IEEE. The 802.11 standard only supports speeds up to 2 Mbps (megabits per second) in the unlicensed 2.4 GHz ISM (Industrial, Scientific and Medical) frequency band. Equipment that conforms to this standard is considered legacy and is no longer being manufactured. It is, however, considered the baseline for IEEE 802.11 WLANs and defined many of the communication concepts still in use today under the newest standards. The most recent revision of the 802.11 Prime standard was published as IEEE Std. 802.11-2007.

802.11b - Created in 1999 as an expansion to the original standard, 802.11b supports a theoretical maximum data rate of 11 Mbps. Published as IEEE Std. 802.11b-1999, the 802.11b standard defines use of the same 2.4 GHz band as defined in 802.11 Prime, and the main focus behind the development of 802.11b was to increase data rates. This standard sparked a huge increase of WLAN adoption, and is considered as one of the main catalysts for the popularity of Wi-Fi today.

802.11a - The 802.11a standard, also created in 1999 as another extension to the 802.11 Prime standard, defines a different modulation technique for communications and operates at a higher frequency than 802.11 Prime or 802.11b. Published as IEEE Std. 802.11a-1999, the 802.11a standard operates in the 5 GHz UNII (Unlicensed National Information Infrastructure) band. Equipment that operates under this standard is not compatible with 802.11b equipment, as they use different frequencies and communication techniques. The higher frequency in use by 802.11a typically shortens the communication range and its ability to penetrate through obstructions, however it has the advantages of higher data rates (up to 54 Mbps) and also does not interfere with the comparatively larger amounts of 2.4 GHz equipment on the market, as the 5 GHz band is much less crowded. Equipment conforming to this 802.11a standard is considered more obscure however can still be found in use today.

802.11g - Published in 2003 as IEEE Std. 802.11g-2003, this standard is backward compatible with 802.11b, and higher data rates up to 54 Mbps are possible. As it uses the same 2.4 GHz band, devices conforming to 802.11g are susceptible to the same interference and can suffer from overcrowding in the frequency spectrum. Devices operating under the 802.11g standard can be configured to communicate directly with 802.11b devices in what is known as mixed mode.

802.11n - This recent amendment (ratified in September 2009 as IEEE Std. 802.11n-2009), introduces many features such as much higher communication ranges and data rates (up to 100 Mbps or more of typical throughput) and a new technology known as multiple-input and multiple-output, or MIMO. This technology uses multiple antennas and multiple wireless connections to achieve these rates, and is much more resistant to interference without requiring a significant increase in power used to transmit the data. MIMO also presents the ability to use multipath (an atmospheric anomaly where a single signal takes different paths and arrives at the receiver at slightly different times, causing a negative factor on performance when using older standards) to its advantage. Many products existed on the market before the standard was fully ratified; often known as "Pre N" or "Draft N", these devices are not guaranteed to fully operate under, or be compatible with, specifications of the completed standard. These draft devices are also not guaranteed to be compatible across differing vendors. At the time of writing, there are concerns that 802.11n devices may greatly interfere with the operation of nearby 802.11b and 802.11g devices and networks; however, there is little doubt that 802.11n represents the next generation of wireless equipment and provides many new features which overcome the problems and limitations of older equipment.