There can be a lot of confusion setting up category pages, as there is a lot of uncertainty about the benefits and drawbacks. Category pages should be set up to have relevant text on them above the listing of blog posts or products. This will help turn the category pages into optimized landing pages.
Unfortunately, a few problems still remain with category (or tag) pages as they can create duplicate content and keyword cannibalization problems; these problems scale exponentially with the size of your site.
This is a problem for both blogs and ecommerce sites as a product or a blog post often falls under multiple categories. As such when the content associated with this item is replicated across all relevant categories, these category pages are inherently populated with duplicate content.
In most cases, the only things that changes on category pages are the duplicate content and the page title. Most category pages either have no text or utilize template text. While this is typically ok as the template text and page title are usually enough for Google to realize which keywords are being targeted, the keyword cannibalization comes into play when you are dealing with category page pagination.
In most cases the template text is repeated across the pagination. Additionally, the page titles either don’t change or simply appends “page 2” to the end of the page title. This means that every paginated category page is targeting the same phrase as the primary category page.
While these problems can seem daunting, there are a few solutions:
To differentiate category pages as much as possible, you should write completely unique text for each category page. While this isn’t the easiest to scale and can be time consuming, creating completely unique text for category pages is significant and is critical to ranking category pages.
To prevent keyword cannibalization, with paginated category pages, you want to put a meta robots “noindex,follow” command on the paginated category pages. This will prevent the paginated pages from being indexed, solving the keyword cannibalization problems often associated with pagination. The reason to use this tag over the robots.txt file is that the meta robots tag will allow search engines to still crawl the page; this will allow search engines to use category pages to discover content and pass any link juice associated with these category pages to the linked to pages.
An Experimental Approach
While the meta robots “noindex,follow” tag is a tried and true tactic that will solve keyword cannibalization problems, any link juice associated with category pagination pages is somewhat lost due to the noindex. This juice can be passed to the pages it links to but this page will not be indexed by Google so it can’t rank for anything.
To maximize the concentration of link juice on the primary category page, you can try implementing the rel canonical tag on the paginated pages. Though this should concentrate the link equity on the primary category page, there can be undesirable effects. Unfortunately since this tag is new and Google does not always treat it the same, there is no guaranteeing the outcome. While I have seen this help, Google may not read the links on the page (though it should). This would be good to test first on a small category to see how Google reacts to this on your site.
Melissa Wright is an experienced SEO with years of helping sites attract visitors. Recently, she has started her own blog, Melissa Writes.