Business owners will often purchase multiple domains to take advantage of all of the keyword potential that is to be had. For example, a webmaster that sells horse shoes online (I’m sure there are some) could own www.horseshoes.com, www.Ilovehorses.com and www.mykingdomforahorse.com. In this example, there are different reasons that this webmaster/business owner owns these different URLs.
The first reason could be that they all represent completely different business entities and/or types of websites and the content on each one is distinctly different from the other one. The person that owns and/or operates these websites has no intention of ever combining or redirecting them anywhere else. They are all websites with completely unique objectives that just happen to have something to do with horses.
The second reason (and usually the most common) is that all of these websites have the same or similar content and all share the same purpose; to sell this business’s horseshoes online. The problems that can incur if not handled correctly is content filtering or, even worse, duplicate content penalties in the search engines. To avoid this, one can employ certain strategies.
Firstly, you can identify which domain you prefer to use as the main domain and simply redirect the other two URLs to it with a 301 redirect. The second and probably the least practical solution is to keep them all separate, but make sure there is absolutely no content overlap. Another scenario would be to use the rel=”canonical” tag which (as of December 15th, 2009) you can use across multiple websites. While the rel=”canonical” link element is seen as a hint and not an absolute directive, Google says that they do try to follow it where possible. This tag lets you set the preferred version of a domain with highly similar content and is used in the section of all non-canonical versions of the site.