WPA stands for Wi-Fi Protected Access and is a subset of the IEEE 802.11i standard intended to replace WEP (Wired Equivalent Privacy) as the primary means of securing 802.11-base wireless networks.

WPA consists of methods to strengthen data encryption (Temporal Key Integrity Protocol [TKIP], message integrity check [MIC], extended initialization vector [IV] with sequencing rules, and a re-keying mechanism) and to provide user authentication. There are actually two authentication mechanisms, one for "enterprise" users using 802.1x and Extensible Authentication Protocol (EAP), and another for home users using a Pre-Shared Key (PSK) method.

Most products now (2007) include WPA support since it is required for WiFi Certification. Older APs may need a firmware update to enable WPA and clients may need an updated driver. Note that you may also experience a loss of throughput when WPA is enabled on some older products.

See our Wireless Security for the Rest of Us article and the Wi-Fi Alliance's WPA Knowledge Center for more information.