bill - 12:36 am on Aug 29, 2007 (gmt 0)

I think you've mixed up the concept of what an RSS file's function is. It's a way to syndicate your content. RSS isn't content. It consists of content from your site...just like the HTML/XHTML pages of your site.

To get back to the original topic...

THE CONCEPT

I think phranque's explanation was right on the money. RSS files perform the function of summarizing your site's content for syndication. Normally your RSS file would contain only recently updated content.

does using RSS affects the site's ranking

It will certainly affect your site's ranking in the blog and feed search engines. Whether it will have much of an impact in the big SEs like Google, Yahoo, and MSN is debatable. There may be a benefit due to the extra exposure an RSS feed can give, but for the most part that seems to be negligible. Adding an RSS fees is no surefire way to increase your SE rankings.

However, adding an RSS feed to your site does have benefits outside the SEs. They help get your content out on the web in front of more people. They also help your visitors to keep tabs on your site.