Structured data: definition, formats and best practices
Updated on February 22, 2026
Quick definition
Structured data is a standardised semantic markup added to a web page's HTML code to help search engines explicitly understand the nature, type and properties of the content presented. Structured data is the technical condition for earning rich snippets and other enriched features in the SERPs.
How it works
Structured data is a bridge between the natural language of your pages and the formal language of search engines. Without them, Google has to infer your content's context from text and HTML structure. With structured data, you communicate directly: 'this page is an article', 'this product costs €49', 'this restaurant is open Monday to Friday'.
The three main formats are:
- JSON-LD (JavaScript Object Notation for Linked Data) — recommended by Google, easy to maintain, separate from HTML
- Microdata — inline HTML attributes embedded in the markup, older
- RDFa — based on HTML attributes, used in specific contexts
The reference vocabulary is Schema.org.
Concrete example: an e-commerce product page with JSON-LD containing `name`, `price`, `priceCurrency`, `availability` and `aggregateRating` will allow Google to display the price, availability and review stars directly in the SERPs.
In 2026, structured data gain importance with the rise of Google's AI Overviews, which rely on them to cite and present information reliably.
Why it matters
Structured data have moved from an advanced optimisation to a standard SEO practice. They condition access to rich snippets, carousel results, knowledge panels and voice assistant answers.
With equal content quality and ranking, a page with well-implemented structured data will achieve a higher CTR than a page without markup.
They also play a growing role in Google Knowledge Graph's understanding of your brand and entities.
How to improve or use it
- 1Choose JSON-LD as the format — recommended by Google.
- 2Identify the relevant Schema.org types for your sector (Product, Review, FAQPage, Event).
- 3Include all required properties and maximise recommended properties.
- 4Test with Google's Rich Results Test before going live.
- 5Monitor the 'Enhanced results' report in Google Search Console to fix errors.
With Sublim
Sublim helps you measure the impact of your structured data on real organic traffic: by tracking the evolution of CTR and organic sessions after activating rich snippets on your key pages, you quantify the concrete ROI of each implemented type — without cookies, in full GDPR compliance.
Frequently asked questions
What is the difference between structured data and Open Graph?
Structured data (Schema.org) is intended for search engines to generate rich snippets and improve content understanding. Open Graph (og:title, og:image, og:description) is a protocol developed by Facebook to control display when sharing on social networks. The two are complementary: Schema.org for SEO, Open Graph for social sharing.
Can structured data penalise a site?
Yes, if implemented in a misleading way. Google sanctions markup of content not visible on the page, manipulative structured data (rating non-existent products, displaying fake reviews), and markup of content not representative of the page. Markup errors do not generate a penalty but make the page ineligible for the corresponding rich snippets.
Does structured data help with voice search and AI Overviews?
Yes. Voice assistants (Google Assistant, Alexa) heavily rely on structured data to identify the answers to provide. Google's AI Overviews also use structured data to better understand and cite sources. In 2026, with the generalisation of conversational interfaces, careful Schema.org markup is a growing competitive advantage.
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