The Heading Tags
Now we are coming to the famous H1 tags. The H(1-6) tags are used to define the headings, H1 defines the most important and H6 the least important heading. In a post or page you should only have one H1 heading (Google dislike more).
<h1>H1 Title</h1>
<h2>H2 Title</h2>
<h3>H3 Title</h3>
<h4>H4 Title</h4>
<h5>H5 Title</h5>
<h6>H6 Title</h6>
The sizes and fonts of heading may be different in your WordPress theme. But you cannot change this size with HTML codes, but only by changing your CSS stylesheet.
Some useful HTML Tags
<hr /> = Horizontal rule: This is also a combined tag.
The thickness and color may vary in your WordPress theme. You can change these in your CSS stylesheet or by using attributes.
<sup> = Superscript: <sup> Superscript Text </sup>
<sub> = Subscript: <sub> Subscript Text </sub>
The following HTML buttons in the text editor can be neglect;
code - close tags and more.