Using subdomains vs registering new domains

I have a few websites with either adsense or affiliate links on them. I have ideas for more, but I was thinking of using subdomains instead of purchasing more domains. Is that a good idea? Each site would be submitted so search engines as site1.maindomain.com and site2.maindomain.com. I know I would have to use that structure throughout the site to avoid referencing to any site accidentally as maindomain.com/site1 because that could cause a duplicate content situation.

Would it be OK to go that route, or should I keep buying domains?

 

Hello, Greenthorn.
Use sub-domains if the stuff you are loading onto them is similar to what you already have in your main domain. Let's say you have a main domain "cars.com". You can then add a sub-domain "porsche.cars.com". If this is not the case, use a different domain altogether. Why? Because it is confusing to people using search engines to have different things hosted under the same domain. Also, the search engines do not recognize sub-domains as separated sections. For them, sub-domains are part of a whole.
Cheers.

 

I agree with everything TechnoGeek said except about serach engines not recognizing sub-domains as different sections. That depends on the search engine and what you consider "separate." For instance, different subdomains can have different silktide sitescores, pageranks, sitemaps, ip's, etc.

 

i agree with you gordaen

 

When we talk for search engines in the back of our head there is a googling bell, so not only subdomains are treated differently but even the same domain without the www. part is different (which in fact is a subdomain too)

 

What I meant when I said that sub-domains are not recognized as independent sections by search engines was based on something that anyone can test: if one makes a search in Google for “site:mydomain.com”, one will get as a result “mydomain.com”, "www.mydomain.com", “something.mydomain.com”, and so on. They are all considered as belonging to the same *site*.

 

Thanks for the replies. It is important for me for google and other search engines to see them as a seperate website. I have rewrite rules in all my .htaccess files to redirect non-www to www to prevent site being indexed twice and resulting in duplicate content. The domain I am planning on using is a five-letter domain, not a word, just an acronym for my business name. So "people" seeing the results in search engines won't be confused by conflicing terms such as car-insurance.vioxx.com