What Structured Data Actually Buys You
JSON-LD structured data doesn't change how your page renders for human visitors — it's a separate, machine-readable block that tells search engines specifically what type of content a page contains (an article, a FAQ list, a breadcrumb trail) using a shared vocabulary (schema.org) that search engines have agreed to interpret consistently. This is exactly what powers "rich results" — the FAQ dropdowns, star ratings, or breadcrumb trails that sometimes appear directly in Google search results instead of a plain blue link.
Getting the schema type and required fields right matters more than it might seem: an FAQ schema needs actual question/answer pairs that genuinely appear as visible content on the page (Google explicitly penalizes structured data that doesn't match visible content), and a Breadcrumb schema needs to accurately reflect the page's real position in the site's navigation hierarchy, not an arbitrary path.
Structured data is a hint, not a guarantee — adding correct JSON-LD markup makes a page eligible for rich results, but search engines still independently decide whether and when to actually display them, based on their own quality and relevance criteria.