In HTML, what does the inserted text (formatting element) do? Does it underline a text? If so, why is it called inserted?

Answer 1

As the playground shows, it underlines a text.

I would assume, the "inserted" stands for its meaning/purpose and underlines the text.
Like there are two tags for bold text, one for "bold" text and one for "more important bold" text, where in the end, both are just bold.