Schema.org
Also known as: Schema vocabulary
In short
A shared vocabulary of types and properties used to describe entities and their relationships in structured data on the web.
Give data a shared meaning
Schema.org supplies names for concepts such as a product, organization or offer. Types describe what an entity is. Properties describe its characteristics or connect it to another entity.
The vocabulary is separate from the format used to publish it. JSON-LD, Microdata and RDFa can express Schema.org data. Choosing JSON-LD determines how you write the information; choosing Product determines what that information describes.
For commerce, distinguishing a product from an offer is useful. The product describes the item. An associated offer can describe the terms under which a seller makes it available.
Illustrative example
Imagine a retailer describing a kettle. A Product record provides the name and brand. Its associated Offer provides a price and currency. A parser can identify which number is the price rather than guessing from nearby page text.
This is a conceptual example, not a complete implementation or a list of required properties.
Check the consuming service
Schema.org defines a broad vocabulary. A search engine or other consumer may support only a subset and impose additional requirements. Valid vocabulary alone does not guarantee eligibility for a specific display. Confirm the consumer’s documentation and keep the markup consistent with the information customers can see.