Use heading tags to emphasize important text
Heading tags (not to be confused with the <head> HTML tag or HTTP headers) are used to present structure on the page to users. There are six sizes of heading tags, beginning with <h1>, the most important, and ending with <h6>, the least important (1).
<h1>Brandon's Baseball Cards</h1>
<h2>News – Treasure Trove of Baseball Cards Found in Old Barn</h2>
<p>A man who recently purchased a farm house was pleasantly surprised … dollars worth of vintage baseball cards in the barn. The cards were … in news papers and were thought to be in near-mint condition. After … the cards to his grandson instead of selling them.</p>
(1) On a page containing a news story, we might put the name of our site into an <h1> tag and the topic of the story into an <h2> tag.
Since heading tags typically make text contained in them larger than normal text on the page, this is a visual cue to users that this text is important and could help them understand something about the type of content underneath the heading text. Multiple heading sizes used in order create a hierarchical structure for your content, making it easier for users to navigate through your document.
Imagine you're writing an outline
Similar to writing an outline for a large paper, put some thought into what the main points and subpoints of the content on the page will be and decide where to use heading tags appropriately.
Use headings sparingly across the page
Use heading tags where it makes sense. Too many heading tags on a page can make it hard for users to scan the content and determine where one topic ends and another begins.