SEO Advice: When To Use Subdomains
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March 09, 2007
As a professional Search Engine Optimizer, I am frequently fielding
questions asked by those lucky few who are new to the SEO field, and
among these so-called "newbies" a recurring question often pops up -
"Which of the following ways is best to structure site URLs?"
- www.site.com/subfolder OR
so, it is with this recurring quandary in mind that I will attempt to
answer the question, "which URL structure is best in terms of SEO,
subfolders or subdomains?"
Short Answer: If the breadth
of an issue or keyphrase will be covered in such detail that a new
website should be constructed to best accommodate the content, or more
simply, if the site’s graphical navigation will need to be altered, use
subdomains. In all other cases, use subfolders.
Long Answer: To answer this question in detail, we’ll need to go over a few key facts regarding subdomains, subfolders and site themes.
- Represented in the URL by the characters after "http://" and the ones before ".site.com"
- Are viewed by Search Engines as totally unique sites independent of the parent domain.
Authority (in other words, the ability for the site and its subsequent
pages to rank in the search engines) is not passed down from the parent
- Can be listed on the first page of the SERPs along
with main domain pages. Feasibly, all 10 of the results on the first
page of a search engine could be subdomains of a single parent domain.
- Represented in the URL by the characters after ".site.com/" and before "filename.html".
- Are viewed by Search Engines as a subdirectory within a site.
- Site Authority is passed down from the main domain.
- At most, one subfolder can appear on the first SERP from the same domain or subdomain.
a general rule, the more focused the theme of a site the easier it is
for that site to rank for keywords directly related to its theme.
- Is defined using all of the site’s pages, not just the homepage or top subpages.
So here’s the long answer:
Search engine optimization is all about driving the most traffic.
Where the goal is to build an authority site with lots of great content
that will be found by search engine driven visitors using laser-target
search terms, as well as unique, "long-tail" search terms that most
would never think to optimize for, but appear on pages in the
subfolders of your site and drive traffic just the same.
subdomains may appear sexy because they can lead to a potentially
larger number of back-links (though not if each subdomain is hosted on
the same IP), or they can sway the SERPs in your favor by crowding out
the top positions with your pages. But without proper promotion, a
subdomain only stops potential laser-targeted as well as "long-tail"
search visitors from finding your site.
My advice is only to
use subdomains when the amount of content on a given topic is so
burgeoning that it requires a separate navigation and design (i.e. its
own website), or is of great enough quality that it will acquire links
and stand on its own.
- If you have a 15
page site about your lawn-care service, and 10 of those pages revolve
around a special fertilizer you’ve developed, you may consider creating
"specialfertilizer.site.com" so that you can market your fertilizer
- Take my company’s domain "objectwareinc.com".
Recently, we built a subdomain "palm.objectwareinc.com", because we had
so much information regarding our wireless application development
solutions that it only made sense to create a separate site for it.
this example, the focus is narrow but there is still an extensive
amount of content. So we’re sending visitors to the subdomain using
targeted keywords while visitors are also finding us using "long-tail"
searches and landing on the pages of palm.objectwareinc.com subfolders.
The overall lesson here is to create subdomains ONLY when you have the quality and/or quantity of content to support them.
Remember that subdomains are independent sites in the eyes of the
search engines, meaning that in order for them to rank, they will
require promotion and link building efforts.