Schema.org gives names to things a page might be about: an Article, an Event, a Product, a DefinedTerm, a Dataset. Marking a page with the right type turns prose into data, so a machine does not have to infer that a list of names with dates is a conference calendar.
The vocabulary is expressed in a page through a syntax, most commonly JSON-LD in a script tag. The vocabulary and the syntax are separate things and are often confused: Schema.org is the dictionary, JSON-LD is how you write it down.
The discipline that matters is honesty. Schema is a claim about the page, and marking up a rating you do not have, or a list a reader cannot see, is the kind of mismatch search engines penalise rather than reward.
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Frequently asked
Does Schema.org markup improve rankings?
Not directly. It makes a page eligible for rich results and helps machines understand what the page is, which affects how and where it appears rather than where it sits in the ordering. The effect is real but it is about presentation and comprehension, not position.
What is the difference between Schema.org and JSON-LD?
Schema.org is the vocabulary, the agreed list of types and properties. JSON-LD is one of the formats for writing that vocabulary into a page, and the one Google recommends. You can express Schema.org in microdata or RDFa instead, but almost nobody does any more.
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JSON for Linked Data: the structured data format Google, AI engines, and other crawlers prefer for embedding schema.org markup in pages.
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Structured data that tells a machine a page is a ranked or ordered list, and names the items in it with their positions.
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