WPA/WPA2-Personal (PSK) stands for Wi-Fi Protected Access with a Pre-Shared Key, and was developed by the Wi-Fi Alliance to address the security weaknesses associated with WEP security. WPA/WPA2-Personal (PSK) is a standards-based security technique where each packet of information is encrypted with a different code, or key. Since the key is constantly changing, WPA/WPA2 is very secure. The encryption key is generated automatically from a string of characters called the pass phrase or from the use of a Pre-Shared Key (PSK).
Wi-Fi Protected Access (WPA) is an interim standard adopted by the Wi-Fi Alliance to provide more secure encryption and data integrity while the IEEE 802.11i standard was being ratified. WPA supports authentication through a Pre-Shared Key (known as WPA Personal), a new encryption algorithm known as the Temporal Key Integrity Protocol (TKIP).
WPA2 is a certification available through the Wi-Fi Alliance that certifies wireless equipment as being compatible with the 802.11i standard. The goal of the WPA2 certification is to support all the mandatory security features of the 802.11i standard.
All clients must use the same Pre-Shared Key (PSK) to connect to a network encrypted with WPA. The PSK can be any word or phrase from 8 to 63 characters. Watch out for upper- and lowercase differences ("n" is different than "N"). Remember, the easiest way to break your security is for someone to guess your PSK.