HTML is vry important and integral part of SEO. As doing On-page SEO is dependent on the ease of the HTML and how better you know it. Though HTML is not very difficult to learn for SEO needs. As a SEO Professional involved in On-Page SEO , you will be interested in those changes made in HTML 5, which will affect your work. As this is still very new so here are some of them:
1. Improved page segmentation. Search engines are getting smarter and they are applying page segmentation into their consideration. Basically, page segmentation means that a page is divided into several separate parts (i.e. main content, menus, headers, footers, links sections, etc.) and these parts are treated as separate entries. In present HTML, there is no way for a Web master to tell search engines how to segment a page but this is bound to change in HTML 5.
2. A new "article" tag. The new tag is the best addition for a SEO in their profession. This tag allows you to mark separate entries in an online distribution, such as a blog or a magazine. When articles are marked with the tag, this will make the HTML code cleaner because it will reduce the need to use
tags. Also, probably search engines will put more weight on the text inside the tag as compared to the contents on the other parts of the page.
3.There is a new "section" tag. The new tag can be used to identify separate sections on a page, chapter, book. The advantage is that each section can have its separate HTML heading. As with the tag, it can be presumed that search engines will pay more attention to the contents of separate sections. For example, if the words of a searched keywords are found in one section of the page, it means higher relevance of that section for that keyword searched.
4. A new "header"tag is included. The new tag (which is different from the head element) is a boon for the SEO experts because it is very useful. The tag is very similar to the tag but the difference is that it can contain a lot of stuff, such as H1, H2, H3 elements, whole paragraphs of text, hard-coded links (and this is really important and beneficial for a SEO), and any other kind of information you feel relevant to include.
5. A new "footer"tag. The tag might not be as useful as the one, but still it allows to include important information there and it can be used for SEO purposes as well. The and tags can be used many times on one page – i.e. you can have a separate header/footer for each section and this gives really a lot of flexibility and convenience.
6. A new "nav" tag. Navigation is one of the important factors for SEO and everything that eases navigation is always good for everyone. The new
tag can be used to identify a collection of links to other pages.
But still HTML 5 is still to come in the common use. When more pages will be made in HTML 5, search engines will pay more attention to HTML 5. Only then it will be possible to know how exactly search engines will treat HTML 5 pages. Also, it will take some time for browsers to adjust to HTML 5.
Keep waiting for HTML 5 SEO's!!!!!!!