Freebase is closing down and Wikidata is the suggested alternative. A lot of questions have come up. This page answers the most common ones.
How is data from Freebase being migrated to Wikidata?Edit
Google will release the Primary Sources tool to help with data being contributed to Wikidata. The Primary Sources tool will allow participating Wikidata editors to see and merge data into Wikidata. The data will not be simply uploaded to Wikidata, but will undergo human curation by the Wikidata community. An important part of that curation is also to increase the amount of well-referenced data in Wikidata, i.e. to provide primary sources for the statements being uploaded to Wikidata (hence the name of the tool).
Besides the tool, Google will release the data from Freebase in several tranches under a CC0 license. They will first focus on data that enriches the existing data, i.e. that increases the density of relations between Wikidata items. You can help with mapping Freebase properties to Wikidata properties as part of WikiProject Freebase.
What is happening with Freebase’s type system? How does this work on Wikidata?Edit
Freebase and Wikidata have very different ideas of how their schema works, i.e. their types and properties. Freebase has domains, each domain has a number of types, and every type has a number of properties. Wikidata, on the other hand, does away with domains and types (although it has the property instance of (P31), which fulfills some part of the role that types do in Freebase, but there is no special support for it in the code), and relies completely on properties. For some background, you can read this blogpost.
How can I access the data in Wikidata? How can I query Wikidata’s data?Edit
See Wikidata:Data access.
How can I get my data into Wikidata?Edit
What are the main differences between Freebase and Wikidata?Edit
- Wikidata is run by the Wikimedia Foundation, the not-for-profit organization that hosts Wikipedia and developed largely at Wikimedia Germany. Freebase is run by Google.
- Wikidata is running Open Source Software only. Freebase is closed source.
- Wikidata’s data is Open Data under the CC0 license. Freebase’s data is Open Data under the CC-BY license.
- Wikidata allows for references and qualifiers. Freebase has CVTs.
- Wikidata relies completely on properties for modeling. Freebase has types and properties (see question above).
- Wikidata has 58 Million statements on 13 Million items. Freebase numbers 2.9 Billion triples on 47 Million topics. A lot of these differences though come from a difference in counting, and in reality the sizes are much more similar than they look (numbers as of March 2015).
- Wikidata counted more than 15.000 active contributors within the last 30 days. Freebase’s community of volunteers never reached such numbers.
By adding to Wikidata, I have a free ticket into Google's Knowledge Graph, right?Edit
Whereas Freebase was the open core of the Knowledge Graph, this is not true for Wikidata. Wikidata is one source of the Knowledge Graph among many, but does not have the same standing as Freebase had.
The most important source of data for the Knowledge Graph is actually the Web itself. You can mark up your own Websites with schema.org and this will be read and processed by all major search engines.
How can I map my Freebase Mids to Wikidata Qids?Edit
Wikidata has the property Freebase ID (P646) to add the Mid on a Wikidata item. Using WDQ, you can map single Mids to their Wikidata Item Qids, e.g. Query: string[646:"/m/02mjmr"]. You can also download Wikidata data and access Freebase ID (P646) in any of the other ways described here, i.e. from the dump, through the entity API, etc. See Wikidata:Data access for more details.
How can I map a Wikidata property to a Freebase property?Edit
A Wikidata property can be mapped to a Freebase property through the use of equivalent property (P1628)
Where can I learn more about how Wikidata works?Edit
Do I have to register an account?Edit
No, but you can do more things, and make use of more features (like watchlists, for example) with one. Wikidata is one of the Wikimedia Foundation's projects, so if you have an account on another project (such as Wikipedia, Wikimedia Commons, Wikisource, etc), then it will work here.
What kind of concepts and data go into Wikidata?Edit
This is governed by the notability policy.
How can I keep up to date on recent developments?Edit
To keep up with recent developments around Wikidata you can subscribe to our social media channels, mailing lists or the weekly summary. You find links to all of them in the contact section on the main page.
I have more questions. Where do I ask?Edit
For technical questions regarding Wikidata’s software Wikibase reach out to the development team at Wikidata:Contact the development team or the wikidata-tech mailinglist. For questions about content reach out to Wikidata editors at Wikidata:Project chat and the wikidata-l mailinglist. You can reach both in the IRC channel #wikidata on Freenode.