What is a knowledge graph and how does one work?

Even though it probably affects our lives every single day, most of us have no idea what a “knowledge graph” is. Asking your favorite voice assistant what the weather will be like tomorrow? That’s thanks to a knowledge graph.

But what exactly is a knowledge graph? Well, there’s actually some debate on what the best definition is, but a recent research paper put it like this:  

A knowledge graph acquires and integrates information into an ontology and applies a reasoner to derive new knowledge.

In other words, a knowledge graph is a programmatic way to model a knowledge domain with the help of subject-matter experts, data interlinking, and machine learning algorithms. The easiest example is probably the box you see in Google’s results.