Theres a bunch. But the most common are:
802.11a - operates at 5Ghz and transmits data at 54Mbps
802.11b- operates at 2.4Ghz and tranmits data at 11Mpbs
802.11g- operates at 2.4Ghz and transmits at 54Mbps.
802.11n is the newest, it operates at 2.4Ghz but transmits at 140Mbps. These are now availble on MACINTOSH Lights...and they have the new DDR3 RAM also. They are kickin.
Maybe you should read your textbook instead of fishing for others to answer your homework questions. Good luck cheater.