RSS (an acronym for "Rich Site
Summary" and later coined "Really Simple Syndication") is a way for web sites to
summarize their content, such as news
articles, to make it available in a different view.
Yahoo News (RSS) headlines can be viewed like bookmarks in Firefox or viewed like email in Thunderbird.
Many web sites generate RSS feeds such as the
BBC News (RSS), Yahoo News (RSS), and your favorite Blog. RSS comes in many flavors, including RSS 0.9, RSS 1.0, RSS 2.0, and Atom -- and Mozilla Firefox supports them all.
You can find many RSS feeds at:
Technorati, Feedster, and Syndic8.com