Structured data is the quiet language your website uses to explain itself to search engines. When it works, Google can show rich results such as review stars, frequently asked questions, product details, event dates, and recipe information. When it breaks, those enhancements simply disappear, often without any obvious warning on the page itself.

That is why checking your markup before publication matters. JSON-LD, the format Google recommends, sits inside a script block on the page. A missing comma, a misplaced bracket, a wrong property name, or a value in the wrong format can invalidate the whole block. Visitors will still see a normal page, but search engines may ignore the structured data entirely.

Common problems are easy to overlook. Developers copy an example and forget to change placeholder text, use a date format Google does not recognise, or nest an item inside the wrong type. Others add a rating without the required review information, or mark up content that is not visible to readers.…