To most people, A, B, and G are just letters of the alphabet, but these particular letters have special meaning when it comes to WiFi. Each wireless standard has three characteristics that distinguish it:
The radio frequency that it uses
The speed at which the network can transfer data
The physical range of the wireless signal
You should consider all these factors when you're trying to figure out which kind of wireless gear to buy and install in your house.
The next time you hop in the car for a drive, consider that humble radio in the dashboard. It has the power to pull music, news, sports, and mattress commercials down from the airwaves and play them out of your car's speakers. You find your favorite stations by their call letters and the number of the radio frequency they occupy on the dial, like 1010 WINS or KSSS 101.5 FM. Unless you're almost out of range, you hear just the one station you're tuned to.
This is because each radio station transmits on its very own frequency in order to prevent signal overlap—the chaos up and down the dial if all of a sudden a hockey game from one station and a live classical music concert from another were both pouring out of your speakers at the same time. Your home networking radio equipment works on the same concept, but it's limited to just two major radio frequencies: 2.4 gigahertz and 5 gigahertz (GHz).