What is structured data in SEO?
Structured data is machine-readable markup added to a page's HTML that tells search engines what the content means, not just what it says. Google uses JSON-LD (recommended), Microdata, and RDFa. Correct structured data enables rich results, star ratings, product prices, and review counts, where Google still shows them in search listings.
Which structured data types does Google still support for rich results?
Google maintains a current list of supported rich result types at developers.google.com/search/docs/appearance/structured-data/search-gallery. As of 2026, active types that produce visible rich results include: Article, Product (with Review and Offer), Recipe, Event, JobPosting, VideoObject, BreadcrumbList, Organization, and SitelinksSearchbox. Two notable removals: FAQPage rich results were removed in May 2026 (Google Search Central blog, 2026-05-07), and HowTo rich results were removed in September 2023. Both types still validate and are still indexed, they simply no longer produce a rich result in search listings. If your site has FAQPage or HowTo schema from before those dates, it is harmless but does nothing visible in search today.
What is the difference between JSON-LD, Microdata, and RDFa?
All three tell search engines the same thing, they differ only in how and where the markup lives in the page. JSON-LD is a separate <script type="application/ld+json"> block in the head or body, decoupled from visible HTML. Google recommends it because it is the easiest to write, validate, and update without touching visible content. Microdata uses HTML attributes (itemscope, itemtype, itemprop) directly on the visible elements, meaning the structured data and the visible content are the same node in the DOM. RDFa is similar to Microdata but uses a different attribute set and supports more vocabularies beyond Schema.org. In practice: use JSON-LD for new work, handle Microdata if it already exists in a template you cannot rewrite, and treat RDFa as a niche format you will encounter on older CMS outputs.
How do I test my structured data?
Google provides two free tools. The Rich Results Test (search.google.com/test/rich-results) parses your URL or a pasted snippet and tells you which rich results it is eligible for and any errors blocking them. The Schema Markup Validator (validator.schema.org) checks Schema.org compliance independently of Google's rich result rules, useful for catching property name errors that the Rich Results Test might not surface. For ongoing monitoring, Google Search Console's Enhancements section reports structured data errors found during crawling across your whole site, not just a single URL. AuditLamp's audit checks Article, BreadcrumbList, Organization, and several other types on each page and reports missing or malformed properties as scored findings.