The first standard, providing a data rate up to 2 Mbps in the 2.4GHz frequency.
Operates in the 2.4GHz frequency and provides a data rate up to 11 Mbps.
Approved in June 2003, 802.11g was the successor to 802.11b, able to achieve up to 54Mbps rates in the 2.4GHz band, matching 802.11a speed but within the lower frequency range.
The first standard to specify MIMO, 802.11n was approved in October 2009 and allows for usage in two frequencies - 2.4GHz and 5GHz, with speeds up to 600Mbps.
This standard supports data rates up to 3.46Gbps.
802.11ax can deliver a single stream at 3.5Gbps, and with new multiplexing technology borrowed from the world of LTE cellular, can deliver four simultaneous streams to a single endpoint for a total theoretical bandwidth of an astounding 14Gbps.