This may not seem obvious, but RDF is a relational model and as such can be thought of as mapping easily to a relational database. In summary:
- Rows are triple resource URIs (or blank nodes)
- Columns are triple property URIs
- The row/column cells are triple object URIs or literals
Or, more shorter and less accurately:
RDF is a relational model where the columns and rows are infinite and the row and column names are URIs.
which might be short enough for an “elevator-pitch” to somebody familiar with relational systems.
XML of course, isn't relational (in the core, without XLink) and requires its own database systems or is used to just encode application data for transfer, without XML representing all the relationships.