Every site is potentially a pair of sites to the average search
engine; either http://domain.com/ or http://www.domain.com/. Both are possible,
and if there are links to both, then Google, a bird of little brain, thinks there
are two sites, each suffering with Sick Site Syndrome.
might have the same content; identical, in fact; but once links exist to alternative
URLs, then both 'exist' as separate sites. And in most cases, it's the webmaster
who starts the problem by using both versions, either internally, or in submissions
to directories or other sites.
Once the problem exists, then Google will
select one or other form - and not necessarily the one you'd choose - and dismiss
the other as a duplicate. And Google does not like duplication, so that can lead
to weird result listings, and poor ranking for your sick site.
This is because
any page rank, indeed any link benefit, is divided between two sites. The hated
little green bar (Google Toolbar Page Rank) can be useful here - for some sites,
one URL form shows higher than the other. This confirms that there are 'two sites'
in Google's dreams, and that your links are divided.
In an ideal world,
one form would have a page rank of zero, the other would be consistent. And hopefully
substantial! But in the real world, you have a severe case of Sick
Which Should I use?
The choice is yours; convention
says that a full domain will use the www: http://www.domain.com rather
For a subdomain, the subdomain name replaces the
www http://xyz.abc.com, rather than http://www.xyz.abc.com
plenty of sites out there that defy convention, choosing one and sticking with
it is far more important than the choice you make.
How Do I Fix It?
straightforward; use a 301 permanent redirect from http://domain.com to
http://www.domain.com (or vice versa).
If you know what that is,
you'll know if you can do it or not!
If it's too technical for you (it is
for me!), then check your web host's information files, or contact support.
Merging the two URLs brings all your incoming links to ONE site.
This is achieved with a permanent redirect; you need to choose one (usually but
not always the WWW version), and 301 permanently redirect the other URL to the
one you choose. So visitors are instantly and seamlessly (and painlessly and permanently)
taken to one consistent URL.
Convention says use the WWW, while subdomains
do without the www. It's up to you, but I'd argue that 'consumer sites' should
go with the flow, or risk confused visitors (others may disagree!).
done, it really does not matter much how others link to you. Except that consistency
almost certainly means better link benefit from the search engines. But all links
will come to the same place, and searches will eventually feature just the one
URL, and logical, predictable listings format.
The key to success is not only to set up the redirect
correctly - but to check it, by manually typing in a 'deep page' URL in the wrong
form - and see what happens.