Generally serach engine consider Sub Domain as an unique address within the existing domain name and crawl it independently to the main domain name such as http://top9.atspace.com but in case of sub folder serach engine will consider it as a part of the original web site and generally it needn't to add links to the search engines as the main page get crawled it will get listed gradually if it is linked from the home page or other pages within the site. If you are desired to create a site not relevent to the main home page it will better to create sub domain for your site and you should add it independently to the search engines to crawl it properly. But in case of folder you dont need to do such thing
As you mentioned, Google treats a subdomain as a different site from parent site. To get a subdomain to rank well you have to build links to it just as you did for parent site; hence in one respect, starting a subdomain is just like starting out and developing a new domain.
Actually, that may have changed. Will have to wait for more observation, of course, but something definitely switched today. Would love to hear your thoughts on it Smyrl. -Michael
Michael, I was speaking from past experience and not in light of any recent developments (about which I know nothing). I have six subdomains on one site. Parent site: PR 6 - 29 Backlinks Showing in Google Subdomains PR 5 - Backlinks range from 18 - 29 (Older subdomains have more backlinks than most recent.)
Smyrl, I wasn't referring so much to the PageRank, that is treated as page specific, not domain. It's why if you get more links to a subpage than the homepage you can wind up with that page being the highest PR on the site. I was only talking about the fact that it looks like maybe G is treating all subdomains as a single domain now. -Michael
I ran site command and do see subdomain pages showing up. Interesting! I can't wait to see if my newest subdomain gets page rank this update. I have not been link building for it.