From MIT's Technology Review:
Compiling a giant database of all the facts in the world could help Google’s future products understand you better.
For all its success, Google’s famous Page Rank algorithm has never understood a word of the billions of Web pages it has directed people to over the years. That’s why in 2010 Google acquired Metaweb, a company building a database intended to give computers the ability to understand the world. Two years later the company’s technology resurfaced as the Knowledge Graph (see “Google’s New Brain Could Have a Big Impact”). John Giannandrea, vice president of engineering at Google and a Metaweb cofounder, says that will lead to Google’s future products being able to truly understand the people who use them and the things they care about. He told MIT Technology Review’s Tom Simonite how a data store designed to link together all the knowledge on Earth might do that.
What is the Knowledge Graph?
It’s a distillation of what Google knows about the world. An analogy I often use is maps. For a maps product you have to build a database of the real world and know there are things called streets, rivers, and countries in the physical world. That’s creating a symbolic structure for the physical world; the Knowledge Graph does that for the world of ideas and common sense. We have entities in the knowledge graph for foods, recipes, products, ideas in philosophy or history, and famous people. We can have relationships between them, so we can say these two people are married or this place is in this country or we can say this movie is related to this person.
How does that make a difference to Google’s Web search?
We’ve gone up a level from just talking about the words to talking about what the thing actually is. In crawling and indexing documents we can now have an understanding of what the document is about. If the document is about famous tennis players we actually know it’s about sport and tennis. Every piece of information that we crawl, index, or search is analyzed in the context of Knowledge Graph. That’s not the same as completely understanding the text as you and I might do but it’s a step towards it.
We can now do question answering on Google.com, for example you can search for “How old is Barack Obama?” We’re also doing things related to exploration. We have a feature called the carousel for exploring categories of entities, so if you type in “London bridges” it will show you a bunch of bridges.The Knowledge Graph
Being able to understand what people are searching for will, of course, help you target search ads. But does Knowledge Graph have uses beyond search?
Inside Google the Knowledge Graph is a piece of infrastructure and it’s getting larger and broader and deeper all the time. It’s a cross-company effort. Almost all the structured data from all of our products like Maps and Finance and Movies and Music are all in the Knowledge Graph, so we can reasonably say that everything we know about is in this canonical form. It lets our product people in all parts of the company be more ambitious....MORE
