What is "microdata"

In HTML to Microdata API allows us to make the semantic structure a little more specific, defining what is the content of each element.

We add special attributes, itemscope and itemprop. Each element itemscope defines a data item. Each itemprop defines the name of a property. The property value is the content of the HTML tag. A Microdata API provides us with special access to this data.

Source: W3C