Wikidata offers copies of the available content for anyone to download.
Note that there are also several other methods for accessing structured content from Wikidata, which may not require a complete database dump.
JSON dumps (recommended)
JSON dumps containing all Wikidata entities as a list can be found under https://dumps.wikimedia.org/wikidatawiki/entities/. Those are being created on a weekly basis.
The previous location for JSON dumps at http://dumps.wikimedia.org/other/wikidata/ is still maintained, older dumps can be found there.
This is the recommended dump format. Please refer to the JSON structure documentation for information about how Wikidata entities are represented.
Hint: Each entity object (data item or property) is placed on a separate line in the JSON file, so the file can be read line by line, and each line can be decoded separately as an individual JSON object. Note that the entries in the dump do not have to be in order: Q2 doesn't necessarily follow Q1.
Full XML dumps of Wikidata can be found at http://dumps.wikimedia.org/wikidatawiki/.
Warning: The format of the JSON data embedded in the XML dumps is subject to change without notice, and may be inconsistent between revisions. It should be treated as opaque binary data. It is strongly recommended to use the JSON or RDF dumps instead, which use canonical representations of the data!
Incremental dumps (or Add/Change dumps) for Wikidata are also available for download. These dumps contain stuff that was added in the last 24 hours, reducing the need of having to download the full database dump. These dumps are considerably smaller than the full database dumps
They can be found at http://dumps.wikimedia.org/other/incr/wikidatawiki/.
Canonical RDF dumps using the Turtle format can be found under https://dumps.wikimedia.org/wikidatawiki/entities/.
The Wikidata Toolkit project also provides RDF dumps, using a slightly different mapping. These dumps can be found at http://tools.wmflabs.org/wikidata-exports/rdf/. The RDF mapping used by the Wikidata Toolkit is described in the paper Introducing Wikidata to the Linked Data Web.
The complete dumps together contain all entity information in Wikidata with the exception of order (of aliases, of statements, etc.), which is not naturally represented in RDF. Simplified dumps encode statements that have no qualifiers as single RDF triples (references are omitted).
The data model can be looked up here. The data model describes the fundamental building blocks of Wikidata's data.
An overview over the schema of the database can be found at this page. (This is not the schema of the data in Wikidata.)
These databases can be used for personal or commercial use, backups or offline use. All structured data from the main and property namespace is available under the Creative Commons CC0 License. Text in the other namespaces is available under the Creative Commons Attribution/Share-Alike License; additional terms may apply. Media items and other content are available under other licenses, as detailed on their description pages.