This is a good article, thanks for sharing Agnes! It actually looks like
the entire website you found this article at is a good resource for some information on
SEO.
Here's another link you might find useful - it's
a blog written by Matt Cutts (one of the lead guys at Google) he goes into
SEO quite often, and discusses the matter from Google's perspective. I've linked directly to the
SEO category on his blog and started the link to page 2, but you can easily navigate around to read all of his current and previous posts on
SEO.