data-* attributes allow us to store extra information on standard, semantic HTML elements without other hacks such as non-standard attributes, or extra properties on DOM.

What is data attribute used for?

Definition and Usage The data-* attribute is used to store custom data private to the page or application. The data-* attribute gives us the ability to embed custom data attributes on all HTML elements.

What is the data NAV attribute?

The data-navigation-type attribute stores the type or purpose of the navigation.