A feed is a function of special software that allows feedreaders to access a site, automatically looking for new content and then posting the information about new content and updates to another site. This provides a way for users to keep up with the latest and hottest information posted on different blogging sites.
There are several different kinds of feeds, read by different feedreaders. Some feeds include RSS (alternately defined as “Rich Site Summary” or “Really Simple Syndication”), Atom or RDF files.
By default, WordPress comes with various feeds. They are generated by template tag for bloginfo() for each type of feed and are typically listed in the sidebar and/or footer of most WordPress Themes. They look like this:
The first four feeds display recent updates and changes to your site’s content for the different feedreaders. Of these, the RSS feeds are the most well known. The last feed example is used by RSS 2.0 feedreaders and does not show your site’s content. It only shows the comments made on your site.
To track the comments on a specific post, the post_comments_feed_link() template tag is used on single post pages like this:
<?php post_comments_feed_link('RSS 2.0'); ?>
There are ways to modify these feeds, and these are covered in the article on Customizing Feeds.