The first version of RSS was released in 1999 for the my.netscape.com portal. This version became known as RSS 0.9. RSS 1.0 was released in 2000. This new version added XML namespaces support and the enclosure element – which permitted audio files to be carried in RSS feeds and helped spark podcasting. A rival syndication format, Atom, was released in 2003 and has now been adopted as an IETF standard.
In 2005 Microsoft announced that it was adopting the feed icon first used in the Mozilla Firefox browser. A few months later the Opera browser followed suit – effectively making the orange square with white radio waves the industry standard for RSS and Atom feeds.
The strength of XML and reason it was chosen as the base for RSS is that it maintains the separation of the user interface from structured data. Whereas HTML specifies how to display data in a browser, XML defines the actual content. For example, in HTML you use tags to tell the browser to display data in different locations and ways, but in XML you only use tags to describe data, such as a stock price, link location or an image.