HTML · Global attributes

itemid

A unique identifier for an item described with microdata.

htmlRunnable example html course

Syntax

itemid="https://example.com/#course"

Example

Try it

<div itemscope itemtype="https://schema.org/Course" itemid="#css-course"><span itemprop="name">CSS</span></div>

Reference pages are the quick answer. The course explains the why, shows the full example and ends with a challenge.