Direct answer
Structured data should describe the visible page and use types supported by the actual content. Valid syntax creates eligibility, not a promise of enhanced display.
Practical steps
- Choose the primary visible entity.
- Follow feature-specific requirements.
- Serialize JSON-LD safely.
- Validate and monitor rendered pages.
Common mistakes
- Adding facts users cannot see.
- Inventing ratings or authors.
- Assuming validation guarantees a feature.
Limitations
- Eligibility and display change.
- Schema.org vocabulary is broader than Google feature support.
Primary sources
- Understand how structured data works — Google Search Central; current 2026-08-14; 2026-08-14.
- JSON-LD — Next.js; 2026-03-02; 2026-08-14.