Wired Equivalent Privacy (WEP) is a security protocol, specified in the IEEE Wireless Fidelity (Wi-Fi) standard, 802.11b, that is designed to provide a Wireless Local Area Network (WLAN) with a level of security and privacy comparable to what is usually expected of a wired LAN. A wired Local Area Network (LAN) is generally protected by physical security mechanisms (e.g. controlled access to a building) that are effective for a controlled physical environment, but may be ineffective for WLANs because radio waves are not necessarily bound by the walls containing the network. WEP seeks to establish similar protection to that offered by the wired network's physical security measures by encrypting data transmitted over the WLAN. Data encryption protects the vulnerable wireless link between clients and access points; once this measure has been taken, other typical LAN security mechanisms such as password protection, end-to-end encryption, virtual private networks (VPNs), and authentication can be put in place to ensure privacy.
"Major security flaws" in WEP that left WLANs using the protocol vulnerable to attacks (called wireless equivalent privacy attacks) have been identified by several research groups and where available the more secure Wi-Fi Protected Access (WPA) protocol should be used.