Basic diagram for explaining the principle behind the inclusion of structured data on Wikimedia Commons: file pages on Wikimedia Commons (that use Wikitext, templates and categories) will be enhanced with structured metadata from Wikidata (statements that consist of Wikidata properties and items). Note that this graphic is created for purely illustrative purposes of the general principle behind what's happening on Wikimedia Commons; the file page design and the actual data used might be very different from this image!
This scheme is a variant of an earlier version (2014) developed by Fabrice Florin, in this presentation.

It uses File:Van Gogh - Starry Night - Google Art Project.jpg as an example.
Own work
Sandra Fauconnier