First it was
802.11A
then
802.11B
For whatever reason, they skipped letters in-between and went to
802.11G
The latest greatest is
802.11N
In terms of speed, 802.11G gives up to 54Mbps. Since 8 bits = 1 byte, that equals 54/8 = 6.75 Mbytes/sec.
Regarding bandwidth, I've heard different reports that 802.11N is capable of delivering up to five times the speed (270Mbps) and quadruple the range of the widely used 802.11G Wi-Fi technology.
That means you can transmit up to 27Megabytes per second between two computers, without any wires. That is remarkable.
The higher speed possible than what 802.11N can deliver is gigabit [b]wired[/b] network. That means you have to physically connect two computers using cat5 cables, and have gigabit NIC cards in both computers to be able to achieve the promised 1,000 Mbps (125 Megabytes/second).
How about range? How far can 802.11N transmit data? The theoretical distance that 802.11b/g can cover is 100 meters. The latest technology is said to cover up to 4 times that, which means 802.11N is pushing 1/2 kilometer range at 27 MBps.
That means you can play high bandwidth games with your friend who lives half a mile away, without any of you being hooked up to the Internet, and without wires to connect both your computers!
In summary,
802.11B can do 1.3 Mbytes/sec with a max range of 100 meters.
802.11G can do 6.75 Mbytes/sec with a max range of 100 meters.
802.11N can do 27 Mbytes/sec with a range of 400+ meters.