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linked data has been expressed as simply being about one URL, linking, via a rel value (in particular a URL as a rel value) to another URL.
As with other forms of triples data models, linked data can be hard to explain, especially hard to explain as to why it is useful or necessary for anything above and beyond microformats and JSON which are based on a simpler model of objects that have properties with values.
See triples for more on this problem of unnecessary complexity.