I'm running a site, it's an e-commerce site, and I'm planning to do a blog about the same niche, with the idea of link in almost any post to the main site. I'm not sure if this is a good idea, but I think it is. I'm generating more content, so from this point I understand that it's a good idea. My main doubt is, does it exist any difference if I create the blog in a different domain, in a subdomain of the main site, or in a folder of the main site? I don't know if search engines will understand the subdomain even being the same IP as a different site and then outbound links, and whether is better idea to have a folder to avoid to make the blog even more important than the main site. I hope you understand my doubt, even I know I haven't explain it very clear, and hope you can drop your ideas about it. Thanks!
I appreciate, I will do it. I understand that if well know sites like seobook does it, it means something, thanks, the answer was easier than I thought. I hope you don't mind to explain me why, I hope to learn
Here you go: http://www.mattcutts.com/blog/subdomains-and-subdirectories/ Notice the structure as well
remember that blog.yourdomain.com is different from www.yourdomain.com and yourdomain.com. That's why there is so much talk on SEO sites about needing to use 301 redirects to join www.yourdomain.com and yourdomain.com. So naturally, if this is the case you would be better using www.yourdomain.com/blog so that all the traffic and backlinks generated counts towards your single domain host and you benefit from any pagerank and link juice generated.
If you still want a link juice for your blog it would be better if you would use folder for your blog because subdomain is seen by search engine as different domain.
you should use folder structure b'coz sub-domains can be treated as different website by search engines..