A Wi-Fi based wireless network sends signals using radio waves (cellular phones and radios also transmit over radio waves, but at different frequencies and modulation).
In a typical Wi-Fi network, the AP (Access Point) will advertise the specific network that it offers connectivity to.
Today, wireless technology encompasses such diverse communication devices as garage-door openers, baby monitors, walkie-talkies, and cellular telephones, as well as transmission systems such as point-to-point microwave links, wireless Internet service, and satellite communications.
Currently, they are the four major types of WIFI technologies.
Wi-Fi-802.11a.
Wi-Fi-802.11b.
Wi-Fi-802.11g.
Wi-Fi-802.11n.