WEP

Wired-Equivalent Privacy protocol was specified in the IEEE 802.11 standard to provide a WLAN with a minimal level of security and privacy comparable to a typical wired LAN, using data encryption. It's now widely recognized as flawed because of an insufficient key length and other problems and can be cracked in a short time with readily available tools.

WME

Wireless Multimedia Extensions (WME) -- also known as Wireless Multimedia Enhancement or Wi-Fi Multimedia (WMM) -- is a set of features based on the IEEE 802.11e draft standard that provide basic Quality of service (QoS) features to IEEE 802.11 networks. It prioritizes traffic from different applications such as voice, audio and video applications under different environment and conditions. Traffic priority is based on four access categories, listed here in their order of importance: voice, video, best effort (Web surfing and e-mail, for example) and background (applications not dependent upon latency, such as printing).

WPA