Six years ago, a split occurred when two groups laid claim to the name RSS.
Netscape engineer Dan Libby authored RSS 0.90, the first version of the format, in mid-1999. The initials stood for "RDF Site Summary" and it made use of the Resource Definition Framework, a Worldwide Web Consortium (W3C) standard for describing web content so that it's more easily understood by software.
At the urging of Dave Winer of UserLand Software and other early RSS adopters, Libby removed RDF support from RSS 0.91, the second version of the format, upon its June 1999 release, as he explained to the RSS-DEV mailing list:
... the primary users of RSS (Dave Winer the most vocal among them) were asking why it needed to be so complex and why it didn't have support for various features, eg update frequencies. We really had no good answer, given that we weren't using RDF for any useful purpose. ... The compromise was to produce RSS 0.91, which could be validated with any validating XML parser, and which incorporated much of userland's vocabulary, thus removing most (I think) of Dave's major objections. I felt slightly bad about this, but given actual usage at the time, I felt it better suited the needs of its users: simplicity, correctness, and a larger vocabulary, without RDF baggage.
Because the format was no longer built on RDF, the name was changed from "RDF Site Summary" to "Rich Site Summary."
Shortly after the release of RSS 0.91, Netscape stopped publishing its RSS documentation and dropped support for the format on its My Netscape portal, a move that in hindsight ranks among the biggest blunders in web history. The company that made billions by seeing an opportunity in web browsers missed another goldmine in RSS, giving it up just as the format began to spark the boom in blogging and syndication. (They're just now getting back into RSS, with Netscape parent company AOL releasing a new My AOL service that reads syndicated feeds.)
In June 2000, Winer published his own version of RSS 0.91 by fiat, taking input from developers who had continued to use the format in spite of Netscape's abandonment. He explained that it was done without the company's permission or participation, dubbing the new version "Really Simple Syndication."
Neither Winer nor his company, UserLand Software, claimed ownership rights in the RSS format or name. UserLand attempted to register RSS as a trademark in September 2000 but abandoned the effort shortly thereafter.
In December 2000, the RSS-Dev Working Group released a new version of RSS called RSS 1.0, adding RDF back to the format and reviving the name RDF Site Summary. This also was done without Netscape's involvement.
Really Simple Syndication was subsequently released as RSS 2.0 and the two rival RSSes have been battling it out ever since.