Definition - What does IEEE 802.11b mean?
IEEE 802.11b is an amendment to the 802.11 standard for wireless LANs. It is of of the specifications that is more commonly known as Wi-Fi.
802.11b uses the same unregulated radio frequency band of 2.4 GHz that was used by the original 802.11 standard, but operates at theoretical data throughput of 11 Mbps. 801.11.b was rolled up into 802.11-2007 along with amendments a, b, d, e, g, h, i, and j.
This term is also known as IEEE 802.11b-1999
Techopedia explains IEEE 802.11b
The popularity of 802.11b was a big reason for the backwards compatability of 802.11g, and even 802.11n. Some critics of 802.11b suggest that we'd be better off if 802.11b didn't get so popular as it has keept Wi-Fi using the 2.4 GHz range. (The 2.4 GHz range is unregulated, so you can get interference from things like microwaves and cell phones).
The current fastest amendment is the 802.11n, which uses double the radio spectrum compared to 802.11a. The 802.11n operates both the 2.4 GHz and 5 GHz bandwidths and has multiple-input multiple-output (MIMO) antennas. The result of all the amendments and forced backwards compatibility is device makers producing see dual-mode, tri-band, routers. In other words, wireless routers that have radios for 802.11b/g as well as 802.11n.
Coming down the line is 802.11ac, which is expected to be used by manufacturers as early as 2012, despite the fact that the amendment has not been released by the IEEE.