[Microdata](https://html.spec.whatwg.org/multipage/microdata.html#microdata)
is a specification to embed machine-readable data in HTML documents. Microdata
consists of name-value pairs (known as `items`) defined according to a
vocabulary. [Schema.org](https://schema.org/) provides a collection of commonly
used markup vocabularies.

The basic syntax includes the `itemscope` attribute to define an item and the
`itemprop` attribute to describe one of the item's properties. Specify types
using the `itemtype` attribute, which can take values defined in your
vocabulary of choice. For example, `schema.org` defines types such as
`http://schema.org/Person` or `http://schema.org/PostalAddress`.

The following example (from
[Wikipedia](https://en.wikipedia.org/wiki/Microdata_(HTML)#Example)) shows how
to use microdata to describe a person:

    <section itemscope itemtype="http://schema.org/Person">
      Hello, my name is
      <span itemprop="name">John Doe</span>,
      I am a
      <span itemprop="jobTitle">Graduate research assistant</span>
      at the
      <span itemprop="affiliation">University of Dreams</span>
      My friends call me
      <span itemprop="additionalName">Johnny</span>
      You can visit my homepage at
      <a href="https://www.example.com" itemprop="url">www.example.com</a>
      <section itemprop="address" itemscope itemtype="http://schema.org/PostalAddress">
        I live at
        <span itemprop="streetAddress">1234 Peach Drive</span>
        <span itemprop="addressLocality">Warner Robins</span>
        <span itemprop="addressRegion">Georgia</span>.
      </section>
    </section>

See [Test Your Schemas](https://developers.google.com/workspace/gmail/markup/testing-your-schema) to debug
your markup and validate it against the supported schema.