Do you know the <dfn> tag and what it is responsible for?

Yes, I know.

The <dfn> tag (definition element) is used to denote a defining term within the text. It indicates the first or primary use of the term in the context where it is defined.

Example of usage:

<p>
  Markup language <dfn>HTML</dfn> (HyperText Markup Language)
  is used for structuring the content of web pages.
</p>

In this example, the <dfn> tag highlights the term "HTML" at its point of definition.

Some browsers may alter the styling of text inside <dfn>, such as making it italic, but the main purpose of the tag is semantic.