What are Rel=Prev and Rel=Next?
These functions were introduced by Google in September 2011 to help tackle the problem of duplicate content. The Rel=Prev and Rel=Next are added to the HTML code of a website in order to let search engines know that a certain collection of consecutive pages should all be indexed together.
Take a website that has an article or product section that runs onto several pages. Google doesn’t necessarily see them as the same article, instead it would treat them as competing URLs on the same topic.
What do they do?
Rel=Prev and Rel=Next are necessary for content than doesn’t fit onto one page without making the page continue far below the fold. At the bottom of each page there is ‘previous’ or a ‘next’ button. This will take you either to the continuation of the article or the previous page of it.
If you don’t apply these functions, it will be much more difficult for Google to sort the pages. Google may also assume the content isn’t paginated and therefore will treat it as duplicate versions of the same topic.
An example of a rel=prev and rel=next tag in code:
Why is this important for search engine optimisation?
Rel=Prev and Rel=Next allows Google to easier understand what exactly it is looking at and subsequently send users to the most relevant page, which is usually the first page in the series. If they aren’t used you may get a situation where page 2, 3 or 4 of an article is higher in Google’s search rankings than the first page.
We usually recommend avoiding spreading content over multiple pages where possible. With good UX design even long content usually can be made easily readable and navigable.