RSS has a sordid history. Different people and groups have largely unilaterally created specifications that they called RSS. Some RSS formats are XML-based formats. And some RSS formats are RDF-based formats.
The list below is of all known RSS versions. They are listed in chronological order of when they were released.
NOTE: In the list below, although RSS 1.0 seems to be out of place, it is actually in the correct place chronologically.
NOTE: There are 3 different versions of RSS 0.91. Netscape's RSS 0.91 (Revision 1), Netscape's RSS 0.91 Revision 3 and Userland's RSS 0.91.
NOTE: RSS 0.93 and RSS 0.94 were only ever released as "drafts" and never became "final" and thus were not meant to actually be used.
|Name||Status||Release Date||Based On||Author|
|RSS 0.90||March 1999||RDF||Netscape|
|Netscape's RSS 0.91 (Revision 1)||?||XML||Netscape|
|Netscape's RSS 0.91 Revision 3||July 10, 1999||XML||Netscape|
|Userland's RSS 0.91||June 4, 2000||XML||Userland|
|RSS 1.0||Standard||December 9, 2000||RDF||RSS-DEV Working Group|
|RSS 0.92||December 25, 2000||XML||Userland|
|RSS 0.93||April 20, 2001||XML||Userland|
|RSS 0.94||August 19, 2002||XML||Userland|
|RSS 2.0||September 2002||XML||Userland|
|RSS 2.0 (post 2002-11-11)||November 11, 2002||XML||Userland|
|RSS 2.0 (post 2003-01-21)||Standard||January 21, 2003||XML||Userland|