Wired equivalent privacy or WEP is or rather was the means of securing WiFi communications across the air. WEP was considered at the time it was developed in 1999 to be a secure method in which to transfer data over a wireless network. In fact, the belief was that it would equal the security and privacy of a wired or even a cable network. Unfortunately, this proved to be not the case as WEP had numerous flaws which meant it could be easily broken, and now it has fallen out of favor with WAP being the preferred method of encryption. However, WEP was and still is a common option for encryption over WiFi networks. This is because of its simplicity; a user had only to enter a pass phrase that could be translated into a 10 or 26 hexadecimal encryption key. The problem was though that the algorithm could be easily reverse engineered revealing the data n clear text.
There are two methods of authentication when using WEP; open system and shared key. With open system there is actual no authentication only encryption. With shared key there is authentication as well as encryption which would make it appear to be the preferred method of security. However that is not the case as shared key is actually easier to break tan open system and therefore not a good method.
WEP is not considered today to be a suitable method for securing a WiFi network. There are other techniques such as WAP, WAP2 which are more robust and do not suffer from the same flaws.
When offered a choice when connecting to a WiFi network, it is advisable to select WPA over WEP unless security is not a concern.