The WebML data model is a suitable adaptation of conceptual models for data design, as already in use in other disciplines, such as database design, software engineering, and knowledge representation. It is compatible with the Entity-Relationship data model, used in conceptual database design, and with UML class diagrams, used in object-oriented modeling. The fundamental elements of data models are entities, defined as containers of data elements, and relationships, defined as semantic connections between entities. Entities have named properties, called attributes, with an associated type. Entities can be organized in generalization hierarchies and relationships can be restricted by means of cardinality constraints. Instances of entities are considered individually addressable by means of a unique identifier (OID). WebML OIDs are abstract concepts, which can be implemented in alternative ways in the underlying storage manager, e.g., primary keys in a relational data store or XML ID attributes in a XML data source.

The image shows an example of data model, representing information about musical albums, which are composed by artists, about whom are provided some reviews. Each album can contain several tracks.