When you create multiple pages with the same, or highly similar, content, search engines algorithmically pick up on the similarities and either exclude all but one of those pages from search results or show all, but only 1 each time a relevant search is performed.
So, you’re asking, “What’s the problem with that?” Let’s say that you have a website that sells rugs, and in an effort to show up in the search results for everyone, you decide to duplicate one of your pages and just change a few words, so you have a whole list of pages with titles and topics like this:
- Buy a rug today
- Buy a rug cheap
- Buy a rug online
- etc, etc, etc
If the content on each page is essentially the same, search engines pick up on that quickly and decide to show me, the searcher, whichever one they think is relevant. Let’s say your page is the best rug page ever, so I decide to link to it from my blog. Then, my neighbor does a search and finds one of the other pages from the list and links to it from his blog. Now, you have 2 incoming links, but to two different pages, so when the next person searches, the search engine does not have a strong link signal to determine which page is better, but your competitors might only have one page that is awesome and happens to have 10 incoming links. All else being equal, your competitor’s page will outrank you in the search results and will likely get more traffic.
One way to combat this is to use the rel=”canonical” tag in your page header. Rel=”canonical” tells search engines that the canonical, or main, version of the page exists a the link the canonical points at, so when one of the pages on your list gets linked to and search engines follow the link, they can see from your page header that the real version exists somewhere else.
The result of this is that all inbound links to the non-canonical pages count for the canonical version, so when you’re going up against a competitor in the search results, you don’t have one page with 5 links and another with 3 links and another with 8 links going against one competitor page with 10 links. Instead, you have one canonical page with 16 inbound links outranking the competitor page.
How Do You Set-Up a Canonical URL?
A canonical link tag can be added to the header of the HTML page. Just be sure to remember the following:
- Be sure that URLs are normal or standard.
- Modify your Content Management System to show only the URLs you want.
- Once you have chosen your ideal canonical page, ensure that your internal links are consistent so all will lead back to the same site.
On the header of the other pages with less priority or less preference, simply add a tag to show the URL you want Google to index it.
Just add rel=”canonical” link to the head portion on the non-canonical variation of each HTML page and indicate the page of your preference.
If you’re using WordPress, install an SEO plugin, such as WordPress SEO, to ensure that the canonical tag is always present.
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