XWiki Objects
Explanation
XWiki Objects are unique instances of a XWiki Class with unique values defined for each of the XWiki Properties (Data Types) that make up the Class. The Property types (datatypes) are defined for the Class, but the actual values for the properties are defined for the Objects when the Objects are instantiated from the Class. An Object is attached to a specific Page, and each Page can have multiple Objects.
For example, a security right can be added to a Page to control its rights, a blog object is attached to a Page representing a blog entry, and Page tags are also stored as XWiki Objects.
Using Objects, you insert structured information in the wiki, while in a traditional wiki you can only enter unstructured information (plain text). This is one of the reasons why XWiki is a second generation wiki.