The Google Knowledge Graph is a knowledge base used by Google and its services to enhance its search engine's results with information gathered from a variety of sources. The information is presented to users in an infobox next to the search results. Knowledge Graph infoboxes were added to Google's search engine in May 2012, starting in the United States, with international expansion by the end of the year. The information covered by Google's Knowledge Graph grew quickly after launch, tripling its size within seven months (covering 570 million entities and 18 billion facts) and answering "roughly one-third" of the 100 billion monthly searches Google processed in May 2016. It has been criticized for providing answers without source attribution or citation. Information from the Knowledge Graph is presented as a box, which Google has referred to as the "knowledge panel", to the right (top on mobile) of search results. According to Google, this information is retrieved from many sources, including the CIA World Factbook, Wikidata, and Wikipedia. In October 2016, Google announced that the Knowledge Graph held over 70 billion facts; by May 2020, this had grown to 500 billion facts on 5 billion entities. There is no official documentation of how the Knowledge Graph is implemented. It is used to answer direct spoken questions in Google Assistant and Google Home voice queries.
Google announced its Knowledge Graph on May 16, 2012, as a way to significantly enhance the value of information returned by Google searches. Initially only available in English, the Knowledge Graph was expanded in December 2012 to Spanish, French, German, Portuguese, Japanese, Russian, and Italian. Support for Bengali was added in March, 2017.
The Knowledge Graph was powered in part by Freebase.
In August 2014, New Scientist reported that Google had launched Knowledge Vault. After publication, Google reached out to Search Engine Land to explain that Knowledge Vault was a research paper, not an active Google service, and in its report, Search Engine Land referenced indications by the company that "numerous models" were being experimented with to examine the possibility of automatically gathering meaning from text. The Knowledge Vault was meant to deal with facts, automatically gathering and merging information from across the Internet into a knowledge base capable of answering direct questions, such as "Where was Madonna born". In a 2014 report, the Vault was reported to have collected over 1.6 billion facts, 271 million of which were considered "confident facts", deemed to be more than 90% true. It was reported to be different from the Knowledge Graph in that it gathered information automatically rather than relying on crowd sourced facts compiled by humans.
By May 2016, knowledge boxes were appearing for "roughly one-third" of the 100 billion monthly searches the company processed. Dario Taraborelli, head of research at the Wikimedia Foundation, told The Washington Post that Google's omission of sources in its knowledge boxes "undermines people’s ability to verify information and, ultimately, to develop well-informed opinions". The publication also reported that the boxes are "frequently unattributed", such as a knowledge box on the age of actress Betty White, which is "as unsourced and absolute as if handed down by God".
According to The Register, the implementation of direct answers in Google search results caused significant readership declines for Wikipedia, from which the Knowledge Graph obtains some of its information. The Daily Dot noted in 2014 that "Wikipedia still has no real competitor as far as actual content is concerned. All that's up for grabs are traffic stats. And as a nonprofit, traffic numbers don't equate into revenue in the same way they do for a commercial media site". After the article's publication, a spokesperson for the Wikimedia Foundation, which operates Wikipedia, stated that it "welcomes" the knowledge panel functionality, that it was "looking into" the traffic drops, and that "We've also not noticed a significant drop in search engine referrals. We also have a continuing dialog with staff from Google working on the Knowledge Panel".