<em> as in emphasis?

Answer 1

Browsers display <strong> as <b>, and <em> as <i>.
However, the meanings of these tags differ: <b> and <i> define bold and italic text, respectively, while <strong> and <em> indicate that the text is "important".

Answer 2

Yeah. Try this link, it's very useful
https://developer.mozilla.org/en-US/docs/Web/HTML/Element