Wireless networks don't work and are insecure...
Wired ones do work and are more secure.
Del

Wikipedia or a web search will give you the answers you have requested.

http://en.wikipedia.org/wiki/Wi-Fi

etc. Found in the first hit by putting"wi-fi" into a search engine.

Come on now don't be lazy, a lot of people put a lot of time and effort writing it so people have an easy to access resource for answering simple broad questions.

Wi-Fi is the technology used in a wireless network. Wi-Fi is loosely based on the IEEE standards for 802.11. Wi-Fi comes from the Wi-Fi Alliance and uses over lapping technology that is similar to the 802.11 standards. With the right setting a wireless network can be just as secure as a wired network. The only real disadvantage to a wireless network is the possibility of interference from outside sources.