A blog or a website can be accessed through http://www.example.com or http://example.com. You should always remember that a www and non-www of the same domain are treated as two different URLs by search engines. There are many factors that determine our position in search result pages, one of them is using “www” or “non www” in your domain

Since Google considers these are two different URL’s, there are also chances of search engines considering them as having duplicate content & sharing link benefit problems

Do I have a canonical issue?

Having your pages / posts indexed as www & non-www is known as a canonical issue. To know if your site has a canonical issue perform a site: search in Google

site:http://example.com

The above search will find all pages indexed under the domain including the www and non-www versions. If you have a look through what is indexed, if you find both www and non-www pages indexed you have a canonical problem.

Which is the most preferred one?

There is no such preference from search engines. It’s up to you to decide on one version, “www” or “non www” and be consistent with it with during your linking building efforts. So it’s always a good practice to select one among www or non www for your site and redirect the unused to the preferred one.

Also, the no. of incoming links will also differ if you keep two versions of your site which ultimately affects the page rank, and the link juices flowing in from all those links get split between the two URLs.

I have already built up backlinks to both versions “www” & “non www”?

Canonical Issue

Not to worry. You can choose your preference and set up a 301 Permanent Redirect. Once the redirect is in place the link juice will be passed to your preferred version and your visitors will also be directed to your preferred version when the unused URL is keyed in. The major search engines have the ability to determine that www and non-www versions are the same and combine the results (passing all the benefit to just one version). Occasionally, they fail to do so – which is when you need to set up a 301 permanent redirect

If you are facing a canonical issue and interested in setting up a 301 Permanent redirect, please watch out for my future post.