In practice
Mark up what is genuinely on the page — organisation, product, article, FAQ, breadcrumb. Marking up things a visitor cannot see is a manual-action risk.
It rarely lifts rankings directly; it changes how the result is displayed and how confidently a model can quote you.
Why it matters
As more answers are assembled rather than listed, machine-readable facts are the difference between being quoted and being paraphrased away.
Related terms