keyword in domain gives high weightage.

ok.but if pages with errors does that relates SEO?if yes then how?

ok.so do think that does not relates.?

Thanks for your reply.
The information is very useful.but how SEO is related to validation..?

I am asking about validation of page for checking errors and warnings..

I have read the web pages should be validated,.but how does it relates SEO.It the page is having warnings and errors so,how that affects SEO.

What is Server Level optimization?How to do that?

From the following Submissions which gives highest weightage?Which is best method for getting backlinks?
Forum posting / Directory submission / Article submission /Blog Posting.

Just wanted an...

But is Separate domain considered as separate site?

hello,
I have seen some sites with different Sub domains for different services.what is the use of it?