Schema markup

"Schema markup" and "structured data" are the same thing in practice: schema.org is the vocabulary, JSON-LD is the format Google prefers, and structured data is the general term. Nothing turns on which phrase you use.

It does not make a page rank better. What it can do is change how the page is shown — review stars, FAQ accordions, recipe cards, breadcrumb trails, product prices and availability. Only some types earn a rich result, and Google publishes which; marking up everything else is harmless and does nothing visible.

There is one rule that carries a real penalty: the markup must describe content a visitor can actually see on the page. FAQ schema for questions that appear nowhere, review markup for reviews you invented, a price that differs from the checkout — these are policy violations, and the sanction is losing rich results across the whole site rather than on the one page.