Wireless protocols IEEE 802.11 A B G N compared

When buying a wireless router or a wireless network card, have you ever wondered what do these letters next to the protocol 802.11 (a, b, g, and n) really mean? What is the difference between these protocols?

IEEE 802.11 is a set of standards for wireless local area network (WLAN) computer communication. The terms 802.11 and Wi-Fi are often used interchangeably but there is slight difference between the two.

(A) 802.11a
Frequency- 5 GHz  
Typical Data Rate - 23 Mbit/s  
Max Data rate – 54 Mbit/s  
Range – 115 feet

(B) 802.11b
Frequency - 2.4 GHz  
Typical Data Rate - 4.5 Mbit/s  
Max Data rate – 11 Mbit/s  
Range - 115 feet

(G) 802.11g
Frequency - 2.4 GHz  
Typical Data Rate – 19 Mbit/s  
Max Data rate - 54 Mbit/s  
Range – 125 feet

(N) 802.11n
Frequency - 5GHz and/or 2.4GHz  
Typical Data Rate - 74 Mbit/s  
Max Data rate - 300 Mbit/s (2 streams)
Range – 230 feet