What is RSS? 
RSS is a Web content syndication format.
Its name is an acronym for Really Simple Syndication.
RSS is a dialect of XML. All RSS files must conform to the XML 1.0 specification, as published on the World Wide Web Consortium (W3C) website.
A summary of RSS version history.
At the top level, a RSS document is a <rss> element, with a mandatory attribute called version, that specifies the version of RSS that the document conforms to. If it conforms to this specification, the version attribute must be 2.0.
Subordinate to the <rss> element is a single <channel> element, which contains information about the channel (metadata) and its contents.