Wi-Fi Protected Access

Wi-Fi Protected Access (also known as WPA and WPA2) is the name for a number of standards to use encryption on a Wireless LAN. They were made because people found many weaknesses in WEP, or Wired Equivalent Privacy (the standard that came before WPA). 
Products that have the label "WPA" were made to work with most cards, even those that came out before there was WPA. This is not true for access points.
Products with the "WPA2" use all of the standard. This started in 2004 and is more secure, but it may not work with some older hardware. 
There are two types of WPA. They are called "WPA Personal" and "WPA Enterprise." WPA Personal is used a lot in casual places like people's homes. To connect, you enter a password. WPA Enterprise is used for bigger networks like businesses. To connect, you must enter a username and password given to you by the people in charge of the network.