1. Short for Wi-Fi Protected Access, WPA is an improved data encryption standard introduced with the 802.11i wireless standard in 1999 that helps reduce the security vulnerabilities with WEP. For wireless computer networks, WPA2 (Wi-Fi Protected Access II) provides security and encryption for data transmissions and general computer connectivity and is a replacement for WPA. WPA2 was made available in 2004 and all network devices from 2006 and on are required to be WPA2 certified. Devices prior to 2006 may or may not be compatible with WPA2.
WPA and WPA2 were developed as a response to weaker security found in WEP (Wired Equivalent Privacy). However, despite providing more advanced security and encryption protocols, WPA2 still has one major flaw. The Wi-Fi Protected Setup feature makes it possible to bypass WPA2, which essentially breaks the security in many cases. Security is still stronger than WEP or WPA in any case, allowing for 256-bit encryption using a security key of either 64 hexadecimal digits or a passphrase of up to 63 ASCII characters.
2. Short for Windows Product Activation, WPA is Microsoft's method of authenticating the Microsoft Windows user is the authorized owner of the copy of Microsoft Windows being used on the computer to help prevent piracy. WPA started first being used in all versions of Windows, including consumer versions, with the introduction of Microsoft Windows XP. When a user first installs Microsoft Windows XP they must authenticate with Microsoft by transmitting hardware information about the computer to Microsoft, that information helps to generate a unique key that is assigned to the CD-Key included with Windows. Once created Microsoft is able to distinguish if the CD-Key being used is being used for the same computer it was assigned to.