When Google first announced the Knowlege Graph, it named Freebase as one of its primary sources of structured data. It was named as one several public sources of information, which also included Wikipedia and the CIA World Factbook.
Google announced that it will be closing Freebase, and moving toward the Wikimedia Foundation's Wikidata, which is described as "a free linked database that can be read and edited by both humans and machines". It acts as "central storage" for the structured data of Wikipedia, Wikivoyage, Wikisource, and others.
WIkidata has simply been improving better than Freebase, so Google has decided to support that instead, and will be working to transition Freebase data over to Wikidata appropriately.
"When we publicly launched Freebase back in 2007, we thought of it as a 'Wikipedia for structured data,' So it shouldn't be surprising that we've been closely watching the Wikimedia Foundation's project Wikidata] since it launched about two years ago," Google's Freebase says in a Google+ update (via Search Engine Roundtable). "We believe strongly in a robust community-driven effort to collect and curate structured knowledge about the world, but we now think we can serve that goal best by supporting Wikidata -- they’re growing fast, have an active community, and are better-suited to lead an open collaborative knowledge base."
We should note that while Freebase has been around since 2007, it's only belonged to Google since the company acquired Metaweb in 2010.
Google is helping transfer Freebase to Wikidata, and in the middle of next year, it will wind down the Freebase service as a standalone project. They'll also launch a new API for entity search powered by Google's Knowledge Graph.
"Loading Freebase into Wikidata as-is wouldn't meet the Wikidata community's guidelines for citation and sourcing of facts -- while a significant portion of the facts in Freebase came from Wikipedia itself, those facts were attributed to Wikipedia and not the actual original non-Wikipedia sources," Freebase explains. "So we’ll be launching a tool for Wikidata community members to match Freebase assertions to potential citations from either Google Search or our Knowledge Vault, so these individual facts can then be properly loaded to Wikidata."
You may remember hearing about Knowledge Vault earlier this year.
It's a system of Google's, which stores information so that machines and people can read it. It's basically Google's giant database of facts. When you ask Google questions and get those direct answers, they're likely coming from there. Rather than relying on crowdsourcing info like the Knowledge Graph, it uses an algorithm to pull info from the web, and turn it into raw data. You can get more in depth into it here.
"We believe this is the best first step we can take toward becoming a constructive participant in the Wikidata community, but we’ll look to continually evolve our role to support the goal of a comprehensive open database of common knowledge that anyone can use," Freebase says.
Before the end of March, Google will launch a Wikidata import review tool and announce a transition plan for the Freebase Search API & Suggest Widget to a Knowledge Graph-based solution.
On March 31, Freebase will become read-only, the website will no longer accept edits, and they'll retire the MQL write API.
On June 30, they'll retire the Freebase website and APIs.
Image via Freebase