RSS has been described as Tivo for the Internet...Netflix for the Internet...Podcasting for more than just audio...
"[RSS] Feeds are a way for websites large and small to distribute their content well beyond just visitors using browsers. Feeds permit subscription
to regular updates, delivered automatically via a web portal, news
reader, or in some cases good old email. Feeds also make it possible
for site content to be packaged into "widgets," "gadgets," mobile
devices, and other bite-sized technologies that make it possible to
display blogs, podcasts, and major news/sports/weather/whatever
headlines just about anywhere."
-Google's Feedburner Help Center - Feed 101 Page
Image courtesy of http://www.backinskinnyjeans.com/2006/09/how_to_explain_.html