Recently, we reported that Gary Illyes from Google had officially stated that 30x redirects no longer diluted PageRank – which was surprising news for many people in the SEO community.
Up until now, if you had migrated your site from one URL to another, the most practical means of doing so whilst maintaining any PageRank value attributed to the original pages was by means of 301 page redirects – which tell the search engines that any change of domain address is permanent.
According to the revelations provided by Google’s Mr Illyes, you might easily be led to believe that a webmaster can use any type of redirect interchangeably, almost arbitrarily, with little cause for concern in terms of losing out on those hard won SEO gains which are attached to the original page addresses.
However, it turns out that the use of 301s still makes a lot of sense – particularly if you are using page redirects for canonical purposes.
So, Why Use 30x Redirects Anyway?
The purpose of 30x redirects is to fix broken page links by telling a user or search engine (by giving the browser a new URL address to load instead) where a piece of content can be found when the original page has been moved or made unavailable. This might be because a site address has been permanently changed owing to a corporate rebranding exercise, or owing to some temporary reason.
As we mentioned earlier, a 301 redirect tells the user (or search engine) that the change of page URL is in fact permanent, whereas a 302 redirect is only a temporary change which will soon revert to its original address.
It was a firm belief that any link juice associated with a page URL could only be passed on to a new page when 301s were used, but Gary’s statement has changed all of this by informing us that 302s (and any other 30x redirects) also pass full PageRank value on to the new address – either temporarily or forever.
And What Exactly Are Canonical Links?
In the simplest of terms, a canonical link is the exact URL name that you want a search engine to use as the definitive, most authorative, address for a given page of content. There are many issues which can easily arise when multiple URLs exist for the same page and, without the use of canonicalization, these issues can cause serious problems in terms of SEO performance. Duplicate content is one such issue.
Consider the following list of URL addresses:
If a user can arrive at a given page by means of any of these addresses then so can a search engine.
So which URL will be used to crawl, cache and index your home page?
The correct answer is all four – if a canonical link is not provided!
By telling Google (and other search engines) what the preferred URL is for a given page of content, the duplicate content issue is resolved as the search engine knows exactly what is happening when it encounters four versions of the same page – which basically serve as a single page with four different ways of arriving at it.
Similarly, instead of PageRank being shared by these four versions of the same page – the link juice acquired by each version is accumulated and passed on to the preferred, or canonical, version of your homepage URL.
Now, instead of providing four complete versions of the same page of content – you can simply use a canonical meta tag in the header of any duplicate pages which point to the main URL – or use a 301 redirect instead.