Do sub-domains help overall domain ranking?

[reddogmusic]

If I have a blog at (for example) blog.mywebsite.co.uk (hosted on Wordpress), does this confer rankings to the top level domain (e.g. www.mywebsite.co.uk which we host ourselves)? Contained within the blog are many links to the main website (which is an eCommerce website) for all our key phrases, but it seemed like a good idea to keep the blog and the store separate.

Alternatively, would it be better to use something like www.mywebsite.co.uk/news?

Thanks!

Alex

[itrogers]

Revisiting this - check out this Quora thread with some additional insight. http://www.quora.com/Search-Engine-Optimization-SEO/Do-sub-domains-hurt-SEO

[itrogers]

You are right in that you would be better off having your blog in sub-directory rather than in a sub-domain.

Sub-domains are very close to being considered the equivalent of a new root domain. For example, Wordpress.com and Blogspot.com blogs come automatically registered with a new subdomain. There are hundreds of thousands of these blogs, but only a few actually have any authority despite the authority of their root domain.

When you create content on your blog in a sub-directory, your inbound links to those posts will help the authority of the domain you are on. So links to www.example.com/blog will help you out much more than blog.example.com.