Structured data is standardised markup added to a web page's code to describe its content in a language machines understand without ambiguity. The reference vocabulary, Schema.org, has been maintained jointly by Google, Microsoft and others since 2011; the recommended format today is JSON-LD, a small block of text invisible to the visitor but explicit for robots. Where a human guesses that "Open Tuesday to Saturday, 9am–7pm" is an opening schedule, the machine needs to be told formally — which is exactly what the markup does.
For a local business, the schema types that matter are few and highly profitable. LocalBusiness (or its variants Restaurant, Store, HairSalon…) describes the establishment: name, address, phone, hours, service area, price range. Service and Offer describe what you sell and on what terms. FAQPage marks up your questions and answers — valuable for AIs even since Google restricted its rich display. Review and AggregateRating carry your reviews. Article structures the blog, and BreadcrumbList the breadcrumb trail.
For years, the selling point was rich results in Google — stars, hours, prices right on the results page. That still holds, but a second argument has overtaken it: structured data is AI assistants' favourite food. When ChatGPT or AI Overviews need to recommend a restaurant, an establishment whose menu, hours and reviews are cleanly marked up is one they can cite without risk of error — and AIs favour what is reliable. Markup has become one of the technical pillars of AI search optimization.
Two traps to avoid: marking up information that is false or absent from the page (Google penalises it, AIs lose trust), and letting the markup drift from reality — a schema showing outdated hours is worse than no schema at all. That is why markup must live with the site: on the sites I build and maintain, it is updated together with the content.
Common mistakes
- Describing what isn't on the page : marking up reviews or prices absent from the visible content breaks Google's rules and can trigger a penalty.
- Choosing the wrong type : using Organization instead of LocalBusiness (or vice versa) deprives you of key fields like opening hours or service area.
- Forgetting to test : a single syntax error invalidates the whole block. Google's Rich Results Test avoids nasty surprises.