WEP, WPA and WPA2

WEP  

The Wired Equivalent Privacy (WEP) protocol was defined in the late 1990s for encrypting wireless communications. Within several years, flaws were found in the algorithm, and tools are available today to break WEP encryption in minutes.

How to break WEP encryption?

http://docs.lucidinteractive.ca/index.php/Cracking_WEP_and_WPA_Wireless_Networks

http://www.smallnetbuilder.com/wireless/wireless-howto/30114-wep-crackingreloaded

http://forums.remote-exploit.org/tutorials-guides/1556-newbie-guide-how-crack-wep-key-step-step-another-newbie.html

http://lifehacker.com/5305094/how-to-crack-a-wi+fi-networks-wep-password-with-backtrack

Wireless networks should use the Wi‐Fi Protected Access (WPA) or WPA version 2 (WPA2) encryption, both of which are stronger than WEP.