What it means
Structured data is the umbrella term for any data on a webpage organized in a way that machines can parse without ambiguity. In SEO, structured data almost always refers to schema markup implemented as JSON-LD or microdata.
The opposite is unstructured data - plain prose, image content, and free-text HTML where a machine has to guess at the meaning of each element.
Why it matters
Search engines and AI engines were designed to interpret unstructured data, but they do it imperfectly. Adding structured data removes the guesswork. When you tell Google your business name, address, phone number, and opening hours through schema markup, Google does not need to extract those facts from your contact page footer.
For AEO, structured data improves citation accuracy. AI engines that pull from your site for an answer can lift facts directly from the schema rather than from prose, reducing the risk of hallucination.
How it's used
Common structured data formats on a service business website:
- LocalBusiness, Organization, Service schema for the core entity
- Review and AggregateRating for testimonials
- FAQPage for FAQ sections
- Article with Author for blog posts
- BreadcrumbList for navigation
Implement as JSON-LD in the page head. Validate with the Schema Markup Validator.