What are databases?Edit
For our purposes, databases organize, represent, store, and make-searchable information.
There are many kinds of databases. You might have heard about "relational databases" because they are very common and display information in tables (rows and columns), like a spreadsheet.
As databases have advanced, programmers have been able to associate data with specific entities like people (ex. "Person A" has an address, age, occupation, etc.)
This is possible by using unique identifiers (and identifiers in general) to describe relationships.
Document-oriented databases are designed to structure data this way. Wikidata is a document-oriented database.