from "About Feed Syndication" from FeedBurner.com
RSS is a standard for publishing regular updates to web-based content. Using this standard, Web publishers provide updates, such as the latest news headlines or weblog postings. Meanwhile, consumers use RSS reader applications (or one of a growing number of online services) to collect and monitor their favorite feeds in one place (RSS content from a publisher, viewed in one of these readers, is often called a "feed").
Consumer Bottom Line: RSS makes reviewing a large number of sites in a very short time possible.
Publisher Bottom Line: RSS permits instant distribution of content updates to consumers.
Who publishes RSS feeds?
Some of the biggest names on the web now offer content using RSS feeds:
In addition, thousands of weblog authors publish feeds to keep themselves better connected to their readers/admirers/critics. Blogs are a driving force behind a recent surge of interest in RSS and syndicated content.