Describe visible, accurate information
Structured data gives machines a consistent way to interpret certain page details. Select a schema type only when it accurately represents visible content and the site is eligible under current search-engine policies. Do not mark up claims, reviews, offers or locations that visitors cannot verify on the page.
Validate the implementation
Use JSON-LD or another supported format, escape generated values correctly and check required properties with official testing tools. Validate after template changes and monitor search reports for errors. A technically valid item may still be ineligible for a search enhancement.
Treat enhancements as optional
Search engines choose whether to show enhanced results, and formats and eligibility can change. Markup does not guarantee rich results, indexing or higher positions. Google's structured data guidance explains the rules and supported features.