Structured data is machine-readable markup that describes what a page contains. It does not lift a page's position directly, yet it can change the traffic that position produces.
Search engines cannot infer everything from text
A crawler reading a page sees words and layout. It can guess that a number is a price or a rating, but guessing carries a risk of being publicly wrong.
Structured markup removes the guesswork by labeling values explicitly: this is the author, this is the preparation time, this is the event date.
Because the labeling follows a shared vocabulary, the same markup is readable by multiple engines and by other systems that consume web content.
Enhanced results are a display decision
Where an engine trusts the markup, it may render the result with additional elements such as review stars, prices, availability or a list of subsections.
Those elements occupy more vertical space and give the user more reason to choose that result over its neighbors before clicking anything.
The engine decides whether to display them. Valid markup makes a page eligible, and eligibility is not the same as entitlement.
Click-through rate is the mechanism, not ranking
An enhanced listing usually attracts a larger share of the clicks available at its position, which is why the effect is often mistaken for a ranking improvement.
The distinction matters for measurement. Position may be unchanged while traffic rises, and a report tracking only average position will show nothing at all.
The effect also cuts both ways, since a visible rating that compares poorly with competitors can reduce clicks rather than increase them.
Markup must describe what users actually see
Engines require the marked-up content to be present on the page for the user. Describing reviews that do not appear, or prices that differ from the page, is a policy violation.
Enforcement is typically the withdrawal of enhanced display for the site, which removes the benefit while leaving the implementation work in place.
Keeping markup synchronized with the page is therefore an ongoing engineering obligation, especially where content is generated from a database that changes.
Coverage decides whether the work is worthwhile
The value of structured data scales with how many pages can carry it and how often those pages appear in results where an enhancement is available.
Sites with large repeated templates, such as product catalogs, recipe archives or event listings, gain the most because one implementation covers thousands of pages.
A handful of hand-marked pages on a small site rarely justifies the effort, which is why structured data is usually a template project rather than a content task.