HTM or HTML Extension?

HTM or HTML Extension?
When you save an HTML file, you can use either the .htm or the .html extension. We use .htm in our examples. It is a habit from the past, when the software only allowed three letters in file extensions.
With new software it is perfectly safe to use .html.
HTML Headings:
HTML headings are defined with the <h1> to <h6> tags.
EXAMPLE:
<h1>This is a heading</h1>
<h2>This is a heading</h2>
<h3>This is a heading</h3>

HTML Paragraphs
HTML paragraphs are defined with the<p>tag.