All of them. Headlines form the semantic backbone of every document and should be used according to their hierarchy. This does not only help your readers but also makes it possible for machines to better understand and work with complex documents, if the headlines are used correctly.
Another advantage that speaks for the correct use of headlines is user behaviour. Many users will only “scan” a document, which means they will simply look at the headlines. If an article has multiple headlines, arranged in a sensible fashion, it becomes easier for the reader to capture the content and meaning of the article. This also hold true for machines, like the GoogleBot.
HTML-specification for Headlines according to W3C
This is the hierarchy for headlines within a document. There is only one H1 headline:
<h1>Headline with the topic of the document </h1> <h2>Introduction</h2> <h2>Advantages</h2> <h3>A detailed look at an advantage </h3> <h2>Conclusion</h2>
A heading element briefly describes the topic of the section it introduces.
There are six levels of headings in HTML with H1 as the most important and H6 as the least. Visual browsers usually render more important headings in larger fonts than less important ones.http://www.w3.org/TR/html4/struct/global.html#h-7.5.5
Should you use the keyword within the headline?
Yes. But not out of hope for a better ranking on the search result pages.
The keyword that best describes the topic of the document should be in the headline, for the user. For this, it makes sense to add the keyword to the H1 headline, if possible even at the very beginning of the headline.
What do I have to keep in mind when using headlines?
Many Content-Management-Systems (short CMS) will also use the “H1” of an article to form all or part of the page title.
Additionally, the title of an article is used by many Content-Management-Systems as the page title for the document.
That is why it will appear in the search result pages, in this form. It should also be mentioned that social media platforms like Facebook or Google+ use and display the page title as a preview for the website they link to.
The title element is a strong ranking factor and should therefore have the keyword, for which the page (URL) is supposed to rank well, as its first word.
So how do I write a good SEO-headline?
The same way that you would write a good SEO-text. Which is not at all.
Just as there is no “SEO-text” you should not work on a “SEO-headline” – or even think about writing one. Use headlines that help your users and try to keep all the possible questions in mind, that the topic of your page might entail.
There are also a few helpful tips that can send you on your way to great headline design. Jakob Nielsen, a usability expert and author, advises to set up a headline according to these characteristics:
- short and concise, 5 words or less
- high information content
- begins with the keyword
- makes sense and is understandable even without having read the article
- is predictable / fits the reader’s expectations
David Ogilvy was probably the internationally most prominent writer of advertisement copy. He once said:
On average, five times as many people read the headline as read the body copy. When you have written your headline, you have spent 80 cents out of your dollar.– David Ogilvy
Should I use multiple headlines on a page?
Sure, if you offer enough content on your page (URL) and your headline-hierarchy makes it easier for a user to comprehend the article. Ideally you will only use one H1 headline per document . Please do not try to use multiple headlines on a page just for the sake of having multiple headlines on the page. Headlines are not about quantity – what matters here is relevancy and how useful they are.