Search algorithms frown on anything that could be misconstrued as manipulating search results.
What are H1 tags?
Search engines evaluate the content on each page using the "header" tags. It tells the search bots what is important.
The header HTML code affects the size of the font, and the empty space above and below the text. This is shown below:
H1 header example.
H1 headers are the most important. Most likely it should be similar or match the title of your page. Search engines think this is really important to verify quality content. One H1 tag is best.
H2 header text example.
H2 are like chapter titles. If someone just wanted to look at the headers to skim the content, they should be able to gather some insight on the information. Search bots do the same thing.
H3 header text example.
H3 is more like a topic within a chapter.
H4header text example.
H5 header text seems more likely to be integrated into a paragraph.
H6 header text gets really small. Don't know why I would even use this?
A RECOMMENDATION FOR BETTER SEARCH RESULTS:
Organize the content on your website or blog using the formatting tools to create "headers" throughout the page. Headers tell search engines and readers what is important content on a page and verifies quality information. Learn to prioritize your content with headers for better SEO.
HTML Code for headers is written like this list below.
<h1>This is heading 1</h1>
<h2>This is heading 2</h2>
<h3>This is heading 3</h3>
<h4>This is heading 4</h4>
<h5>This is heading 5</h5>
<h6>This is heading 6</h6>
In this video below from Google Webmaster Matt Cutts answers, Is "More than one H1 on a page good or bad?"?Harriete Estel Berman