What is Structured data?

Structured data is information about a page written in a fixed, machine-readable format. Where the visible page says “Sourdough starter kit, $24, 4.7 stars from 312 reviews”, structured data states the same facts as labeled fields — this is a Product, this is its price, this is its aggregate rating — so software doesn’t have to guess.

Vocabulary and syntax

Two layers are involved, and people often mix them up:

• The vocabulary defines which things and properties exist. For search, that is almost always schema.org; see schema markup.
• The syntax is how you write it into the page. Google supports JSON-LD, Microdata and RDFa, and recommends JSON-LD.

Here is the same fact in two syntaxes:

<!-- Microdata: attributes on the visible HTML -->
<div itemscope itemtype="https://schema.org/Product">
  <h1 itemprop="name">Sourdough Starter Kit</h1>
</div>

<!-- JSON-LD: a separate script block -->
<script type="application/ld+json">
{"@context": "https://schema.org", "@type": "Product", "name": "Sourdough Starter Kit"}
</script>

JSON-LD usually wins in practice because it sits apart from the layout: a redesign won’t break it, and it’s easy to generate straight from a database.

Why it matters

Structured data makes pages eligible for rich results such as product prices, review stars, event dates and breadcrumbs. Google is clear in its introduction to structured data that markup enables eligibility; it doesn’t guarantee a rich result, and it isn’t a general ranking boost.

For AI search, structured data is a clean statement of facts: who wrote a page, when it was updated, which organization stands behind it, what a product costs. Google says AI Overviews need no special markup, but consistent entity data reduces ambiguity for any system that reads your pages.

Common mistakes

• Marking up what users can’t see — reviews, prices or questions that aren’t on the page. Google’s structured data policies treat this as spam and can apply a manual action.
• Stale values, such as a price or stock status in the markup that no longer matches the page.
• Plugin pile-ups: the theme, an SEO plugin and a shop plugin each output their own Organization or Product with conflicting data.
• Chasing features that are gone: HowTo rich results were dropped in 2023, and FAQ rich results stopped showing for all sites in May 2026. FAQPage is still valid schema.org markup, but it no longer changes your listing.

Where to start

Most sites get the most value from a small set: Organization (or LocalBusiness) and WebSite on the homepage, BreadcrumbList across the site, Article on editorial pages and Product on product pages. Add more specialized types only where the content genuinely fits.

Validate it

The schema markup validator extracts JSON-LD, Microdata and RDFa from a live page, checks the JSON syntax and Google’s required and recommended properties for common types, and flags types that no longer produce rich results.

Frequently asked questions