WiFi is an acronym for Wireless Fidelity. WiFi connection uses radio signals very much like mobile phones and other like devices. Here an antenna transmits the radio signals, translated by a computers wireless adapter card. The signal transmitted is then received and decoded by the router. The information is again sent to the cyberspace using an Ethernet cable or Local Area Network (LAN).
WiFi service is bi-directional. The process explained works the other way too. It is a bipartisan radio communication that sends and receives signals in the form of radio waves. In the other way, the cabled Ethernet that gives the Internet connection ships the information to a router. The router then translates and transmits the signals to the computer's wireless adapter card.
The radios used in WiFi converts radio waves into binary codes and vice versa. They are very much the same as in mobile phones and walkie-talkies. WiFi can transmit high frequencies and hence they can handle and deliver lots of data. 802.11 IEEE is the standard used and followed by WiFi's. A WiFi could efficiently transmit three frequency groups. It can use any of the three frequencies without any interference. This is the reason why multi wireless devices get connected to the same wireless connection at the same time.
A mobile device, one like a laptop with a wireless card is required in order to use the WiFi. Latest laptops have built-in wire free cards. With older computers you can use a wireless adapter. A desktop also has a PCI slot where a wireless card can be put in. A wireless router connects to a cabled Ethernet and acts as a gateway to the main entry point. You need to set up the router with default settings. If you live in a multi storied building you can opt to change the settings to avoid interference.
To have your wireless device protected, always use a username and password. Mobile computing is gaining popularity these days and we should obviously thank the public WiFi hotspots. Public networks available are shown on your computer, the moment you turn on. You can choose the one you want and get connected. Some networks ask for username and password. This happens when the network charges for usage.