WEP or Wired Equivalent Privacy or that is what it was supposed to be. Using encryption keys of up to 104 Bit length (up from 40 bit in the original release) it has failed to live up to its name. It is still being used in the IEEE 802.11 wlan standard, although better technologies (WPA) are available.
WEP encoding is considered insecure as it can be cracked in as little as 5-10 minutes, reconstructing the code from in and out going traffic. Yet, it is still better than no encryption at all, when used as a deterrent, assuming you don’t want to create an open free-for-all network.