What is microdata?

The same product in both formats

Microdata, woven into the visible markup:

<div itemscope itemtype="https://schema.org/Product">
  <h1 itemprop="name">Ceramic pour-over dripper</h1>
  <img itemprop="image" src="/img/dripper.jpg" alt="White ceramic dripper">
  <div itemprop="offers" itemscope itemtype="https://schema.org/Offer">
    <span itemprop="priceCurrency" content="EUR">€</span>
    <span itemprop="price" content="24.00">24.00</span>
    <link itemprop="availability" href="https://schema.org/InStock">
  </div>
</div>

JSON-LD, in one block that is separate from the layout:

<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Ceramic pour-over dripper",
  "image": "https://example.com/img/dripper.jpg",
  "offers": {
    "@type": "Offer",
    "priceCurrency": "EUR",
    "price": "24.00",
    "availability": "https://schema.org/InStock"
  }
}
</script>

Both describe the same thing and, when complete, qualify for the same rich results.

The attributes

• itemscope declares that the element contains an item.
• itemtype gives the type as a schema.org URL. It goes on the same element as itemscope.
• itemprop assigns a property. Its value is the element's text, or the src, href, content or datetime attribute, depending on the element.
• A nested itemscope on an element that also has itemprop creates a sub-item, like the Offer above.
• <meta itemprop="..." content="..."> and <link itemprop="..." href="..."> supply values that are not shown as text.

How it compares in practice

Microdata's one real advantage is that the data is the content, so it cannot say something the page does not show. Its cost is fragility: a redesign that drops a wrapper div silently breaks an item, and nobody notices until rich results disappear.

Problems to look for

• Two sets of markup. A theme outputs microdata and a plugin adds JSON-LD for the same thing. Search engines then see two Products or two Articles, often with different values. Keep one source.
• Unclosed scope. An itemprop outside any itemscope is ignored, and a scope closed too early loses its later properties.
• Missing machine-readable values. A price written as "from €24" needs a content attribute with the number.
• Confusing it with microformats. Class names such as hentry and vcard in older WordPress themes are microformats, a different and older convention. They are not microdata.

Check any page with the Rich Results Test, which parses microdata, RDFa and JSON-LD alike.

Should you switch to JSON-LD?

If your microdata is complete and valid, there is no ranking gain from converting it. Switch when you are rebuilding templates anyway, when markup keeps breaking with design changes, or when you add a plugin that outputs JSON-LD and would otherwise duplicate it. On WordPress the usual path is to let one plugin generate JSON-LD and remove the attributes from theme templates; our guide to adding schema markup to WordPress covers the setup, and the schema markup generator writes JSON-LD you can compare against.