The WEP (otherwise known as Wired Equivalent Privacy) standard refers to one of the first encryption policies ever made for wireless network security that's presently been rendered obsolete by the WPA (otherwise known as WiFi Protected Access) and WPA2 standards.
In turn, a WEP key serves as a security password or passphrase used by WEP-enabled WiFi networks in order to protect and secure your network access.
Moreover, WEP keys also enable a number of machines residing within a local network (such as a home-based one) to send and receive encoded correspondences with each other while concealing the contents of these clandestine messages from any and all outsiders.
One lock leading to your humble abode, the WEP key is designed to enable you and you alone to access one access point to the worldwide web.
If you don't have someone else's house key, you won't be able to gain unauthorized access to his home; in turn, if you don't have another user's WEP key, you are conceivably locked out of his wireless network access point to a certain degree (since WEP is flawed by design and can be broken through using a variety of other methods that manipulate or bypass WEP key protection).
In other words, a WEP key is designed to give you and your machine exclusive access to the Internet or some other computer network.
Nevertheless, having a WEP key whenever you're forced to use the outdated WEP standard is better than having no protection at all, truth be told.
A WEP key serves as sufficient protection against script kiddies or inexperienced hackers who are trying to use your WiFi access point for malicious purposes.
Password keys are always a good addition to your network data protection whether you're using WEP or WPA standards, because it generally prevents intruders from gaining unauthorized connections through your WiFi service.
Novice cyber hijackers who lack the scripting ability to crack or hack their way through your WEP key protection has only one way to access your network, and that's to ask you for your password point black.
In fact, the house key analogy works quite perfectly in this instance too.
There are many other ways for experienced burglars to bypass or break down your locked door (WiFi access point) without your house key (WEP key).
Also, even though more advanced home security systems (WPA and WPA2) are available, your house key (WEP key) is perfectly serviceable against everyday, ordinary system protection.