If vocabularies such as the Dublin Core can be considered children of RDF, then RSS is the specification's rebellious teenager. RSS, or RDF Site Summary (and sometimes Rich Site Summary or Really Simple Syndication) is primarily used for syndication and aggregation. O'Reilly's news service, Meerkat, with its continuously updating news headlines, uses RSS for its data feeds.
RSS is also the most prevalent implementation of RDF in the world at this time, primarily through its use in weblogging and with popular online media outfits such as BBC News, Salon, Wired, and others. (If you're not familiar with weblogging, weblogs are online journals that are usually updated daily, with most recent entries showing at the top of the page in a reverse chronological order. Weblogging, or blogging as it's frequently termed, has increased in popularity in the last few years, and estimates now put the number of weblogs at more than 500,000 in the world.)
In order to keep up with your favorite news sources or weblogs, you can visit each one in turn, or you can subscribe to the site's syndication feed. This feed contains the most recent weblog entries, their titles, the URL for each entry, and a brief description of the article or posting, all documented in RSS.
This chapter takes a detailed look at the RSS specification and its history as well as example RSS feeds. In addition, the chapter will also take a look at popular aggregators?tools that process RSS?as well as examples of how to process the content.