What is schema markup?
Structured data added to a page using the schema.org vocabulary so search engines can understand its meaning and show rich results.
Schema markup is what makes a recipe show ratings, a product show stock and price, an event show date and venue, and an FAQ show expandable questions in Google search results. It's structured data, usually expressed as JSON-LD in a <script type="application/ld+json"> block, that uses schema.org's shared vocabulary so any consumer can understand it.
Beyond Google rich results, schema markup is also what AI overviews, answer engines, and product feeds parse to ground their responses. As LLMs increasingly source from structured data over scraped HTML, the value of clean schema markup is going up, not down.
You don't need to memorize every schema.org type. The high-ROI ones: Article, Product, Organization, FAQPage, Breadcrumb, WebSite, Recipe, Event. Pick the ones that match your content, validate with Google's Rich Results Test, ship.