H1 is a specific piece of HTML code that is usually wrapped around text. It was originally meant to display that text as the largest text on the page.
When Cascading Style Sheets (CSS) were developed, one of the things CSS allowed web developers to do was to take the standard H1 format and adjust it (color, typeface, font size) to match the rest of the page design. This meant that sometimes the H1 was no longer the largest text on the page.
As you can see, the H1 tag is pretty important for SEO, usability, and accessibility.
Ideally, you should have one clearly marked on each page of your site.
Also be careful to ensure that the H1 reinforces the point of the page, and that there is only one H1.
While officially it’s OK to have more than one H1 on a page, and Google says use as many as you want, it only makes sense that Google would either:
- Place the majority of the weight on the first H1 they encounter (Bing is on record as doing this).
- Distribute the weight evenly across all H1s, thereby diluting the value of all of them.