I'll make an exemple. Imagine that you are someone who regulary check yahoo's news :
http://news.yahoo.com/news?tmpl=index&cid=716
But you are bored to reload the page every five minutes to see if there is a change. Then juste take a rss feeder program, and configure it to check this url :
http://rss.news.yahoo.com/rss/topstories , which is the rss feed of the news page. Then each time there is a change, the rss feeder program will inform you, so you can go and see the news