Structured data is a standardised block of code added to a web page that labels its content in a form machines can read reliably. It states plainly that a page describes a product, a store, an event or a recipe, and supplies details such as price, address or opening hours.
Most sites use the shared vocabulary from schema.org, usually written in JSON-LD, a format placed in the page's code separately from the visible text. Search engines read it to confirm what the page is about and may use it to show enhanced results, sometimes called rich results, with items like ratings, availability or event dates. Not every markup type triggers a visual enhancement.
Retailers add Product and Offer markup to ecommerce pages, LocalBusiness markup to store pages, and FAQ or Article markup to help content. Hospitality venues can describe menus, opening hours and reservation links. The same markup helps AI tools extract accurate facts.
Pitfalls include marking up information that is not visible on the page, which breaches search engine guidelines, letting prices or stock in the markup drift out of date, and copying code with placeholder values. Errors are easily introduced when templates change. Validators such as Google's Rich Results Test and the Schema Markup Validator help catch problems, and Search Console reports issues found across a site.
Structured data matters because it reduces ambiguity. Clear labels give search engines and AI assistants confidence in the facts, supporting both traditional SEO and newer generative engine optimisation efforts.