Schema.org

What it is

Schema.org is the shared structured-data vocabulary maintained collaboratively and adopted by Google, Microsoft, Yandex, and other major engines. It defines a hierarchy of types and properties that describe real-world things, content, and relationships.

Why it matters

It gives AI search systems a common, machine-readable language for the entities on a page, which improves how those systems classify content and resolve it to known entities rather than guessing from raw text.

How it works

Authors select the most specific applicable type from the Schema.org hierarchy, then describe it using that type's properties, usually serialised as JSON-LD in the page head.

When it applies

It applies whenever a page describes a recognisable entity or content type that engines and answer engines may need to interpret precisely.

Examples

• Marking an article with the Article type and an author property pointing to a Person
• Describing a business with LocalBusiness, including address and openingHoursSpecification
• Using Product with an aggregateRating to express review data

How it is measured

• Proportion of pages emitting valid Schema.org types versus total pages
• Type specificity (use of the narrowest applicable type rather than a generic parent)
• Count of validation errors and warnings per page
• Coverage of recommended properties for each chosen type