So numismatics is exceptionally lucky to have a well developed disciplinary ontology and thus a well established culture of using linked open data, all thanks to nomisma.org.
However, what the heck an ontology actually is and why it is essential to how we use and build digital tools isn’t always super clear, esp. to non-tech people. Max Ved nicely breaks it down for the laiety in these two blog posts:
Liv Mariah Yarrow 