Most sites have some form of pagination in them. Blogs show the most recent articles, then you can click through pagination for lists of older articles. The product listing pages of ecommerce stores have pagination to go through the entire list of products in any category.
Google used to have problems with pagination and sometimes it would rank, for example, page 3 instead of the first page. This is bad because you usually have the first page of the series optimized to be the best user experience.
Google created rel=prev and rel=next tags to better understand pagination. With these tags Google understands when its seeing a paginated series and it knows what the first page of the series is.
For very large sites, pagination can be somewhat important: for small sites it’s usually not important at all unless you know Google is ranking the wrong page of a paginated series.
Here’s how you can implement pagination:
In the <head> section of the page code, include the following for each paginated page:
<link rel=”next” href=”http://www.yourdomain.com/the-next-url.html” />
<link rel=”prev” href=”http://www.yourdomain.com/the-previous-url.html” />
The “next” URL should be the next page in the series: so if you’re currently on page 2, the “next” will be the URL for page 3. Similarly the “prev” URL should be the previous page in the series: so if you’re currently on page 2, the “prev” will be the URL for page 1.
If you’re on the first page, you don’t need to include the “prev” line, and if you’re on the last page you don’t need to include the “next” line.
There is alternate markup that you can use if you have a View All page in addition to your Pagination. I generally don’t recommend using this, because if you have a View All page, that is the one that Google will want to return in search results, and the View All page is usually not the best user experience (if it was, you’d just use that and not have any paginated results, after all).
If you really want to have both pagination and a View All and serve the View All in the search results, instructions for that can be found here.