Structured data
Code added to a web page that tells machines what the page is about, such as a product, its price and its reviews.
Structured data is code you add to a web page that tells machines what the page describes, in a fixed vocabulary. A person reading your product page sees a name, a price and a star rating. Structured data spells out the same facts for a search engine or an AI bot: this is a Product, its price is 49 euros, its average rating is 4.6 from 212 reviews.
How it's written
Most sites write it as JSON-LD, a block of code in the page's HTML, using the types and properties defined by Schema.org. Common types are Organization, Product, Service, Article, FAQPage and Review.
For example, a coffee roaster's page for a subscription might mark up the product's name, its price per bag, the delivery countries and its review rating. None of that changes how the page looks to a visitor.
What it does, and what it doesn't
Google uses structured data to show rich results, such as star ratings, prices and FAQs under a search result. Its introduction to structured data lists which types it supports.
For AI answers the picture is less clear. Google says in its guide to optimizing for AI search that you don't need special markup to appear in its AI features. The facts in your markup should match the text on the page, so the markup helps a machine read what's already there; it can't add facts the page doesn't state.
In AnswerOrbit
Structured data is one of the eight Page checks we run when you check a page for a prompt in Recommendations. A page passes when it carries structured data that machines can read. If it doesn't, the fix we suggest is to add markup for what the page offers, such as Product, Service or FAQ. See Recommendations.