Wi-Fi Protected Access is a data encryption specification for 802.11 wireless networks that replaces the weaker WEP. Created by the WiFi Alliance before a 802.11i security standard was ratified by the IEEE, it improves on WEP by using dynamic keys, Extensible Authentication Protocol to secure network access, and an encryption method called Temporal Key Integrity Protocol (TKIP) to secure data transmissions.

WPA2

Wi-Fi Protected Access 2 is an enhanced version of WPA. It is the official 802.11i standard that was ratified by the IEEE in June 2004. It uses Advanced Encryption Standard instead of TKIP (see above). AES supports 128-bit, 192-bit and 256-bit keys.

Wi-Fi

Wireless fidelity is the generic term for 802.11 technology (see 802.11 above).