802.11
In 1997, the Institute of Electrical and Electronics Engineers (IEEE) created the first WLAN standard. They called it 802.11 after the name of the group formed to oversee its development. Unfortunately, 802.11 only supported a maximum bandwidth of 2 Mbps - too slow for most applications. For this reason, ordinary 802.11 wireless products are no longer being manufactured.

802.11b
IEEE expanded on the original 802.11 standard in July 1999, creating the 802.11b specification. 802.11b supports bandwidth up to 11 Mbps, comparable to traditional Ethernet. 802.11b uses the same radio signalling frequency - 2.4 GHz - as the original 802.11 standard. Being an unregulated frequency, 802.11b gear can incur interference from microwave ovens, cordless phones and other appliances using the same 2.4 GHz range. However, by installing 802.11b gear a reasonable distance from other appliances, interference can easily be avoided. Vendors often prefer using unregulated frequencies to lower their production costs.

Pros of 802.11b - lowest cost; signal range is best and is not easily obstructed.
Cons of 802.11b - slowest maximum speed; supports fewer simultaneous users; appliances may interfere on the unregulated frequency band.

802.11a
When 802.11b was developed, IEEE created a second extension to the original 802.11 standard called 802.11a. Because 802.11b gained in popularity much faster than did 802.11a, some folks believe that 802.11a was created after 802.11b. In fact, 802.11a was created at the same time. Due to its higher cost, 802.11a fits predominately in the business market, whereas 802.11b better serves the home market.

802.11a supports bandwidth up to 54 Mbps and signals in a regulated 5 GHz range. Compared to 802.11b, this higher frequency limits the range of 802.11a. The higher frequency also means 802.11a signals have more difficulty penetrating walls and other obstructions. Because 802.11a and 802.11b utilise different frequencies, the two technologies are incompatible with each other. Some vendors offer hybrid 802.11a/b network gear, but these products simply implement the two standards side by side.

Pros of 802.11a - fastest maximum speed; supports more simultaneous users; regulated frequencies prevent signal interference from other devices.
Cons of 802.11a - highest cost; shorter range signal that is more easily obstructed.

802.11g
In 2002 and 2003, WLAN products supporting a new standard called 802.11g began to appear on the scene. 802.11g attempts to combine the best of both 802.11a and 802.11b. 802.11g supports bandwidth up to 54 Mbps and it uses the 2.4 Ghz frequency for greater range. 802.11g is backwards compatible with 802.11b, meaning that 802.11g access points will work with 802.11b wireless network adapters and vice versa.

Pros of 802.11g - fastest maximum speed; supports more simultaneous users; signal range is best and is not easily obstructed.
Cons of 802.11g - costs more than 802.11b; appliances may interfere on the unregulated signal frequency

802.11n
The 802.11n standard, if agreed upon, stands to replace the current alphabet soup of 802.11 wireless standards, which transmit data at up to 54 Mbps. The basic 802.11n requirements call for a base throughput of 100 Mbps although there have been discussions about usis a very short range (approximately 10 meters) and relatively low bandwidth (1 Mbps). In practice, Bluetooth networks PDAs or cell phones with PCs but does not offer much value for general-purpose WLAN networking. The very low manufacturing cost of Bluetooth appeals to vendors.

What About Bluetooth?
Bluetooth is an alternative wireless network technology that followed a different development path than the 802.11 family. Bluetooth supporting the technology to achieve rates of higher than 315 Mbps. 802.11n uses arrays of antennas, known as MIMO (Multiple In, Multiple Out) to achieve their goals. It is hoped that the standard will be finally ratified in 2006, with products released to market in late 2006 or early 2007.