Companies use subdomains to establish branding and focus on separate products or services, because a subdomain creates a separate URL and in turn a separate web presence, all within your same main hosting account. For example, a restaurant directory may establish sub-domains for different cities, or a school can set up subdomains for different academic programs. Many large Web portals and online retailers structure their sites using subdomains. That structure helps organize diverse topics into a coherent format. Smaller sites use them to save money and boost site promotion efforts. Subdomains may even work for your site, but it's important to understand both the risks and benefits before you decide.

There are some subdomain users that are in serious danger of overkill. You have probably seen it yourself - a site with literally hundreds of subdomains stuffed with keywords that in the vast majority of cases only redirect users to a specific site on the main page.

The Dangers of Subdomain Overkill in SEO

There are a group of website owners and search engine optimizers that rely on subdomains as a way to game their position on search results pages. The simplest explanation of a subdomain is “a domain that is part of a larger domain”. Use of subdomains as a way to move up the search return lists of popular search engines is certainly possible to do, but not without following some very specific, very unproven guidelines. Instead, those sites which use subdomains as a method to structure their sites usually receive better results as opposed to those that simply create hundreds of these keyword dense subsections.
 
What is a Sub-Domain?
The simplest explanation of a subdomain is “a domain that is part of a larger domain”. Sometimes referred to as vanity domains, subdomains (third-level domains) are a popular way to develop web addresses for various sub-sections of your site that you want to differentiate from the rest of your site. You can see an example of this on the WebsiteServices.com website at our classified section - http://classifieds.websiteservices.com. The basic syntax is: "http://subdomain.domain.com". Used correctly, subdomains help websites organize, promote, and reduce fees associated with hosting.

There are many benefits to setting up and developing content on subdomains:

Cost savings: You may or may not save money, so don't get excited yet. Some Web hosts require you to purchase a separate hosting account for each subdomain. Look for a host who allows customers to set up multiple subdomains for no extra hosting costs. It's like getting several different Web sites for the price of one.

Higher search engine rank: You get a boost in most search engine algorithms when you use your important keywords in your domain name. But if you're targeting ten or twelve, they're hard to cram into a single name. Subdomains give you more opportunity to include keywords with your domain.
Easier domain maintenance: With a single domain name, you only have one annual payment, login, and expiration date to remember. The same goes with your hosting account if your host allows multiple subdomains on the same account.

Organizing Topics with Subdomains
Most Web sites have a subdirectory structure. For instance, a Web hosting company might structure their site to include a subdirectory for each type of service:

A1Hosting.com/Basic-Hosting/
A1Hosting.com /Dedicated-Hosting/
A1Hosting.com /Co-location/

The Web hosting company is not just limited to subdirectories however. They can also create separate service specific areas of the site using subdomains. For instance, the hosting company could create a subdomain to explain the individual services or the components of the services such as data transfer, bandwidth or FTP guidance. The advantage for the Web hosting company is an additional opportunity to build and promote a complete online reference for each aspect of their business.

FTP.A1Hosting.com
Bandwidth.A1Hosting.com
Data-Transfer.A1Hosting.com

The benefits provided by subdomains are their ability to provide additional branding and sales opportunities outside of your primary domain name. With a subdomain, you can keep your well-known domain name, yet clearly indicate that each subdomain is a standalone resource.

Advanced Structural Development of Subdomains
To receive the greatest value in terms of site architecture and search rankings, each subdomains should be structured and developed as a completely independent Web site. For instance, in our hosting example the FTP.A1Hosting.com subdomain should have a unique home page created to explain A1Hosting.com’s FTP procedures.

The other pages in the subdomain should be service-specific as well and could cover topics such as anonymous FTP, the number of FTP accounts, FTP restrictions, and any other applicable information related to FTP as it applies to A1Hosting clients.

FTP.A1Hosting.com/ftp-restrictions.htm
FTP.A1Hosting.com/anonymous-ftp.htm

Search engines consider subdomains to be independent Web sites. Instead of buying multiple domains, subdomains provide an opportunity to promote each subdomain independently to search directories because each offers a specific focus and unique content. Hence, the more structured and independent the better chance you have of ranking well for very specific terms and phrases.

Avoid Spamming Penalties

While the majority of websites use subdomains as they were intended, others do not and continue under the guise that the more subdomains exist on a site the greater the chance exists that they can move quickly up the search return lists for hundreds of search terms. While there is no denying that there are potential advantages of subdomains when it comes to the increased number of keyword rankings, many make the mistake of using similar content (often labeled as spam by the search engines). The result of duplicated content is often low rankings and in many cases can result in total delisting from the search engines.

Since low or nonexistent rankings are the lifeblood of your online enterprise, it is essential the the subdomains hosted on your site avoid the use of duplicate content on any page of a subdomain - and that includes the main page (or index page) of each. Take for instance our hosting company. If they were to use the same "sales copy" on each of the main or index pages of each subdomain instead of creating unique content reflecting the focus of that subdomain they risk being perceived as spamming the search engines.

The key to avoiding a "spammy" subdomain is to maintain a consistent theme but creating unique content on each. Since most search engines consider a site's overall theme, websites can have problems if one subdirectory is about dedicated hosting and another is about hybrid automobiles. Subdomains let you create an entire site around a specific subject topic and that is how they are best used.

Content and Site Maintenance with Subdomains
While using subdomains is not (or should not) be considered a salvation to Internet promotional and site development woes, they do work when it comes to forcing you to create unique content as well as organize your Web presence.

Subdomain need to be treated as a separate Web site which means images and content need to be stored separately.  Let's return to the A1Hosting.com example. Although that website may use the same logo, contact information, and basic information about the business, it needs to be saved separately in each subdomain. So each subdomain has its own image folder and Web pages with some of the same information. The owner has to remember to update all of its subdomains each time any common information (such as phone number) changes. Site owners can reduce site maintenance time by using server-side includes if available.

When contemplating the use of subdomains, keep in mind that content is considered by many still more important than the actual site and subdomain structure. Certainly the most difficult and time consuming aspect of online promotions (namely search engine promotion), site owners and online content creators see the greatest traffic benefit by creating valuable content and consistently using important keywords throughout your site. You have many opportunities to include them in subdomain and throughout your site content, namely via the text content on your Web pages, alternate descriptions (or alt tags) on images, well developed meta tags (including the title and description tags) and of course the inclusion of targeted keywords in file and directory names.

Considering Subdomains?
If you are considering using subdomains keep in mind that the proper use (and only the proper use of subdomains) will help you organize and promote your site.  You should be able to set up and manage add-on domains, parked domains and subdirectories from your hosting account or domain registrar control panel. However, as we usually suggest, always consult with your web host before proceeding if you have any doubts.