What is schema markup?
Schema markup is structured data — a standardized vocabulary from Schema.org that describes what a page is about in terms search engines can read directly, instead of inferring it from your prose. JSON-LD is the format Google recommends: a small block of code you drop into the page that labels your content as an article, a product, a recipe, a local business, and so on.
Search engines use that structured data to power rich results — the star ratings, FAQ accordions, price chips, and breadcrumb trails that make a listing take up more space and pull more clicks. Schema doesn't directly raise your ranking position, but the enhanced listings it unlocks measurably lift click-through rate, which is the practical win.