Pretty much every webdev and SEO is familiar with the SE concept, usage of 'keywords'; many webdevs and most SEO's have heard of 'entities' although from comments and questions over the years I suspect few actually understand and readily optimise for entities - they remain 'stuck' with keywords because that is what their tools are built around.
Just as entities are not new - Google acquired MetaWeb in 2010, which accelerated their usage of entities in search - that's 8-years of folks being behind that curve, neither is Google's next big step forward that occurred back in 2013 (5-years ago now) when Google acquired Wavii, which used machine learning enhanced natural language programming to summarise content into structured summaries.
For those wanting to catchup I recommend Bill Slawski's, 03-April-2018, article
3 Ways Query Stream Ontologies Change Search [seobythesea.com], especially the links to additional reading.
Definition: ontology is a formal naming and definition of the types, properties, and interrelationships of the entities in a domain.
Just as PageRank has become but one of umpteen thousand inputs so too have keywords become but a foundation from which much has been built out and up. One may find it beneficial to get past a decade ago in SE mindset.
In case you were wondering why Google has been and is so enthusiastic about webdevs structurally marking up content... can you say free training dataset...
