IEEE 802.11n-2009, or 802.11n, is a wireless-networking standard that uses multiple antennas to increase data rates. The Wi-Fi Alliance has also retroactively labelled the technology for the standard as Wi-Fi 4.

802.11n is an amendment which improves upon the previous 802.11 standards by adding multiple-input multiple-output antennas (MIMO). 802.11n operates on both the 2.4 GHz and the lesser used 5 GHz bands. It operates at a maximum net data rate from 54 Mbit/s to 600 Mbit/s. The IEEE has approved the amendment and it was published in October 2009.

802.11n is a specification for WLAN (Wireless LAN) communications. It is an addition to the 802.11 family of standards, and it will also boost the speed of WLAN (Wireless Local Area Network). Not only that, but also enhance the reliability of the connections, and extend the coverage of the wireless transmission.

802.11n, under its full name IEEE 802.11n-2009, is an old wireless networking standard, announced in its draft format in 2007, and finalized and published in 2009. 802.11n is also referred to as Wi-Fi 4, and it’s the first standard to allow the use of two radio frequency bands: 2.4 GHz and 5 GHz.

802.11n, which once Apple confusingly dubbed "AirPort Extreme" -- the same name the company gave to the earlier 802.11g specification -- is a wireless networking standard first supported by the original Apple TV. Starting on July 20, 2011, Apple quietly started refering to this standard just as 802.11n "Wi-Fi" for simplicity.