A metadata schema is a defined collection of labeled attributes used to describe the content objects in an information space, typically with a required, core set of attributes plus optional ones the schema can extend as needed. For any given project, you have three options: adopt an existing schema as-is, adapt one to your specific needs, or create a new one from scratch.
The Dublin Core Metadata Element Set is the most widely recognized example, originally built to describe web content, now used broadly across digital collections. It defines fifteen elements: Title, Subject, Description, Creator, Publisher, Contributor, Date, Type, Format, Identifier, Language, Source, Relation, Coverage, and Rights. Many real information spaces extend beyond Dublin Core with additional attributes, keywords, audience, security level, industry domain, tailored to what that specific content actually needs to describe.
Dublin Core gives you a solid, well-understood starting vocabulary, but it was never meant to be the last word on what your specific content needs to say about itself.
1: Adopt Dublin Core largely as-is. Academic papers across disciplines are exactly the kind of general, well-understood content Dublin Core was designed to describe, Title, Creator, Subject, Date, and the rest map cleanly onto a scholarly paper without needing much beyond what the standard already offers.
2: Adapt Dublin Core with additional attributes. A pharmaceutical regulatory repository still benefits from Dublin Core's basic elements, Title, Date, Creator, but regulatory content carries requirements Dublin Core was never built to capture, so extending it rather than replacing it entirely is the more efficient path.
A regulatory document repository plausibly needs attributes like approval status (draft, under review, approved, superseded) and regulatory jurisdiction (which country's or region's regulations the document pertains to), neither of which Dublin Core's general-purpose elements capture, but both of which are essential for compliance: someone searching this repository needs to know immediately whether a document is currently valid and which regulatory body it applies to before relying on it. A document expiration or review date is also a reasonable addition, since regulatory documents often have a defined validity period after which they must be reviewed or retired.Organization B, the boutique travel agency, sits somewhere between these two, Dublin Core covers general description well, but a destination guide would likely benefit from adaptations like geographic location or seasonal relevance, without needing anything close to a fully custom schema.