WebID is a way to uniquely identify a person or other agent using a URI
WebID is a replacement for traditional login on the Web. It is an open standard for identity and login. With WebID you no longer need to remember usernames or passwords for all of the sites you use.
‘A WebID is an HTTP URI which refers to an Agent (Person, Organization, Group, Device, etc.). A description of the WebID can be found in the Profile Document, a type of web page that any Social Network user is familiar with.’