A explicit or implicit link between two content objects. It can take the form of one or more of the following:
A reference from an attribute on one of the objects to another
An HTML link (an A or IMG tag, for instance) from the rich text of one of the objects to another
A geographic relationship in the context of a content tree where one object is spatially-positioned in relationship to another
Designing relationships is the core of a relational content model.
Explicit relationships are formed through the usage of an external data structure, for instance a menu or list. The link for the two objects is known only through this external structure.
Implicit relationships are known internally to at least one of the objects. For instance, a child object in a content tree has an internal understanding of its parent object.
A dependency explains that relationships require one content object to depend on another. The management or enforcement of dependencies might prevent an editor from deleting one content object from a relationship until the relationship itself is deleted. In database theory, this is generally referred to a referential integrity.