Knowledge Graph organizes data for presentation around what it calls entities, which include individuals, places, organizations, sports teams, works of art, movies and so on. Information comes from both freely available and licensed sources including the CIA World Factbook, Freebase and Wikipedia. Google launched Knowledge Graph in May 2012 with a base of 3.5 billion facts connected to 500 million entities. By December of that year, the knowledge base had grown to include 570 million entities with 18 billion facts connected to them, and the search engine could recognize three times as many queries as it had initially.
When the search engine recognizes a query related to an entity in its knowledge base, a panel to the right of the search results presents information about the subject including images, important facts, and related searches, with links to explore the subject further. A feature called the carousel, which is being deployed gradually, provides images of related entities above the search results that, when clicked, alter the panel to the right of the results to display their information.
Google offers a brief demonstration of Knowledge Graph: