RSS is a simple XML format popularized originally by Netscape to describe the content of web sites. Aggregators, metasites, and search systems developed tools for reading these files, which was far more illuminating and efficient than analyzing HTML pages. In response to these tools, publishers began to highlight their content using RSS.
The acceptance of RSS snowballed beyond Netscape's expectation as it became particularly popular with publishers of ephemeral content. They saw RSS less as the index to a static site and more as a snapshot of the fleeting contents of a dynamic news source. Even this perspective has been undermined by a more XML-oriented point of view.
Publishers like the BBC, CNET, CNN, Disney, Forbes, Motley Fool, Wired, Red Herring, Salon, Slashdot, ZDNet, and so on see RSS channels as a way to pull in site traffic. The RSS newsfeed is a stream of hyperlinks that function like tiny free banner ads in the global competition for attention.
But for aggregators, XML is the stuff. The web pages with their human-oriented content serve only as backup for these gossipy chains of headlines.
For the meta-publishers, the RSS data is a newsfeed. They build pipelines of information flowing through channels that filter, package, and present these recombinant fragments of interest. These information merchants sell their point of view: the stories are a free commodity, the aggregators market branded discrimination.
The popularity of RSS is due in no small part to its simplicity. Unlike the extensible XML on which it is built, the RSS standard is remarkably closed. Its elements and attributes are (in the pop ular version RSS 0.91) strictly limited in number and size , arguably a problem for publishers but a boon to software developers: We need to consider only a finite degree of software complexity.
The RSS file has a single element called a < channel > . This <channel> has simple descriptive elements, most of them optional, and it contains a series of <item> elements.
An <item> is even simpler. It consists of a < title > (usually a headline), a < description > (usually a brief abstract), and a < link > (presumably to the original news source).