Why it matters
schema.org markup tells search engines what the page is: an article, a product with a price, a business with an address. Without it Google infers that from the text, and rich results such as stars, prices and FAQs are not available at all. It is often sold as a way into AI answers; measured, it is not: a 2025 Ahrefs study of 1,885 pages found no effect on AI citations, and AI assistants fetching a page live do not read JSON-LD. Add it for Google's rich results.
How to fix it
Add a JSON-LD block with the schema.org type that matches the page (Article, Product, LocalBusiness, FAQPage...) and check it in Google's Rich Results Test.