Wikibase/Terms

RDF
Resource Description Framework. A way of representing information in a structured way, used by Wikibase and other software in the Linked Open Data web.

See the W3C's document on RDF concepts.

Statement, triple
In RDF, data is presented in the following form: a subject (item), a predicate (property) and an object (item, quantity, mathematical expression...).
 * Example: " ."
 * Example: " <3.7 million>."

These three pieces of information together are called a triple, and as a single piece of information it's called a statement.

See the Wikidata glossary entry, the Wikipedia article on triples and the W3C's primer.

Item
An object, concept, or event that appears in a triple (the subject, possibly also the object).
 * Examples: "red", "empathy", "New Year's Eve"

See the Wikidata glossary entry.

Property
A descriptor that appears in a triple (the predicate).
 * Examples: "is capital (of)", "inventor (of)", "instance (of)"

See the Wikidata glossary entry.

Cradle
A tool that allows editors to create new Wikidata items using a form (defined by the contents of this Wikidata page).

See the README and the tool itself.

OpenRefine
A tool that can reconcile or import data into a Wikibase instance (including Wikidata).

See OpenRefine's documentation of the tool's Wikibase functionality.

WDQS, query service
Software that provides a way to extract data from Wikibase by using the SPARQL query language.

See Wikidata's query service doc.