Stands for "Wi-Fi Protected Access." WPA is a security protocol designed to create secure wireless (Wi-Fi) networks. It is similar to the WEP protocol, but offers improvements in the way it handles security keys and the way users are authorized.
For an encrypted data transfer to work, both systems on the beginning and end of a data transfer must use the same encryption/decryption key. While WEP provides each authorized system with the same key, WPA uses the temporal key integrity protocol (TKIP), which dynamically changes the key that the systems use. This prevents intruders from creating their own encryption key to match the one used by the secure network.
WPA also implements something called the Extensible Authentication Protocol (EAP) for authorizing users. Instead of authorizing computers based soley on their MAC address, WPA can use several other methods to verify each computer's identity. This makes it more difficult for unauthorized systems to gain access to the wireless network.