What is microdata?
Microdata is the older way of writing schema.org markup, using itemscope and itemprop attributes added directly to the HTML tags a visitor sees, rather than a separate data block.
Where JSON-LD describes a page from a script tag off to the side, microdata is woven into the elements being displayed: a price attribute sits on the actual tag showing the price. That coupling was the original design, and it is also the source of most microdata bugs, since a template edit that changes the visible markup can silently break or detach the data sitting on it.
It still works. Search engines, and presumably any AI crawler that reads schema.org markup at all, read both syntaxes the same way, because the vocabulary is identical and only the wrapper differs. The reason to prefer JSON-LD on a new project isn't that microdata is deprecated, it's that keeping data and presentation in the same attribute makes the data fragile in exactly the way separating them avoids.
Related
- JSON-LDJSON-LD is the syntax for writing schema.org structured data as a self-contained script block, separate from the HTML a visitor actually sees.
- schema.orgschema.org is the shared vocabulary of types and properties, jointly maintained by Google, Microsoft, Yahoo and Yandex, that structured data markup uses to describe things on a page.
- Structured dataStructured data is machine-readable markup, usually schema.org JSON-LD, that states explicitly what a page and its subject are.
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