Silicon Valley.com provides an overview of the basics for wireless at home:

Wireless home computer networking is becoming more and more popular, even as the buying process gets more and more complicated.

Just when consumers were getting comfortable last year with the concept of 802.11b, also known as WiFi, the industry trotted out the 802.11a standard.

When 802.11a turned out to be a flop, the networking industry rolled out 802.11g.
Now the story gets even more confusing with the arrival of A G networking gear that uses both the 802.11a and 802.11g standards.