microdata
Also called: micro data, html microdata
Microdata is an HTML specification that embeds structured data inline in the page body, using attributes like itemscope, itemtype, and itemprop to annotate the same content a visitor sees. It is one of three formats Google supports for structured data, alongside JSON-LD and RDFa.
Microdata lives inside the page body, wrapped around the same text a visitor reads. You mark the boundary of an item with itemscope, name its type with itemtype (usually a schema.org URL), and tag each field with itemprop. Two more attributes, itemid and itemref, give an item a global identifier and let it pull in properties from elements that are not its descendants. All five come from the WHATWG HTML standard, so they are part of HTML itself, not a Google invention.
Microdata vs JSON-LD
Google treats all three formats (JSON-LD, Microdata, RDFa) as equally valid for rich-result eligibility, as long as the markup is correct. It recommends JSON-LD for most sites because the data sits in one script block instead of being interleaved with visible HTML, which makes nested items easier to express and less prone to errors. Microdata still has a place: it binds each value to the exact element a user sees, which can suit simple or annotation-heavy templates where a separate JSON-LD block is awkward to keep in sync.
A minimal product name in microdata:
<div itemscope itemtype="https://schema.org/Product">
<span itemprop="name">Trail Runner 2</span>
</div>Because the annotations are tangled into markup, microdata tends to break on redesigns and template edits more easily than a self-contained JSON-LD block does.
How it affects your traffic
Structured data does not move rankings on its own, but valid markup makes pages eligible for rich results (review stars, product prices, breadcrumbs) that lift click-through from the search results. Microdata that is malformed or interleaved incorrectly silently loses that eligibility, and because it is woven into visible HTML it breaks more often on template or redesign changes than a JSON-LD block does. A Technical SEO pass checks whether your markup validates, whether legacy Microdata should be migrated to JSON-LD, and whether each item type actually matches what the page is.
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