Purpose and content model
Microdata annotates visible HTML with machine-readable items and properties. Itemscope establishes an item, itemtype names its vocabulary type, and itemprop identifies a property. This lets structured information live near the content it describes. It does not guarantee enhanced search results or validate the truth of the information.
Choose a vocabulary supported by the intended consumer and keep its meaning aligned with the visible page. JSON-LD is another structured-data format, but mixing formats carelessly can produce duplicate or contradictory descriptions. The HTML syntax and the vocabulary's own rules are separate concerns.
Syntax and working example
<article itemscope itemtype="https://schema.org/Book">
<h2 itemprop="name">The Balcony Garden</h2>
<p>By <span itemprop="author">A. Reader</span></p>
</article>Supported attributes and behavior
Itemscope is boolean. Itemtype is a space-separated list of type URLs under the applicable rules. Itemprop is a property-name token list. Itemid supplies a global identifier when the vocabulary permits it. Itemref points to IDs elsewhere in the document that contribute properties to the item. Property values are extracted differently depending on the element, such as href on a link or content on a meta element.
Another practical pattern
<div itemscope itemtype="https://schema.org/Event">
<h2 itemprop="name">Seed exchange</h2>
<time itemprop="startDate" datetime="2026-11-14T10:00:00+05:30">14 November at 10:00</time>
</div>Accessibility and browser notes
Structured-data attributes do not replace readable labels, headings, or text alternatives. A search consumer may require additional properties beyond this small syntax example. Keep event times, availability, and other changeable facts synchronized with the actual visible information.
Common mistakes
Do not add hidden ratings, claims, or offers that are not supported by the page. Do not assume an item is complete because it has itemtype. Itemref can accidentally pull in unrelated properties when IDs are duplicated or markup is reused.
Verify your implementation
Validate both HTML structure and the chosen vocabulary using the intended consumer's current tools. Inspect the extracted item, not just the source attributes. Compare every machine-readable value with what the visitor sees and with the underlying business data.
Standard status and sources
Standard; browser availability must be checked independently of specification status.