This diagram is by Christopher Collins at the university of Toronto, published in his paper
DocuBurst: Document Content Visualization Using Language Structure

It shows the contents of a document in a semantic hierarchy. It uses the wordnet lexical database (a human-created database of word relationships).

What I love about it is that the diagram has a conversation with the reader. The middle ring tells the reader that the document is about “physical phenomena”. That’s the most important thing, if the reader shows continued interest, the diagram delivers more and more information in order of importance.

It’s that choice that great information design offers the viewer: the option to read just the top-line or to dive in a get the detail. Websites and showreels do it too sometimes: they ask “How long have you got? 10 seconds, 1 minute, 5 minutes”. The viewer can choose.