HTML Formatting

<b>This is bold text</b>
<strong>This is important text</strong>

<i>This is italic text</i>
<em>This is emphasized text</em>

<mark>This is marked text</mark>
<small>This is small text</small>

<del>This is deleted text</del>
<ins>This is inserted text</ins>

H<sub>2</sub>O
X<sup>2</sup>