Difference Between RSS and Atom

RSS vs Atom | RSS 2.0 vs Atom 1.0

Web feeds are used to publish (in a standard format) information regarding frequent updates like new entries in blogs, breaking news and multimedia to its subscribed readers. Web feeds are very important to publishers because they can automate the syndication process. Web feeds are important for readers because they don’t need to keep track of updates manually. Web feeds can also aggregate many feeds to a single place. Web feeds can be viewed through feed readers (such as Google Reader). RSS (Really Simple Syndication) and Atom are two of the most popular web feed formats used today.

What is RSS?

RSS 2.0 is the latest RSS version, which was the successor to its initial version RSS 1.0. RSS 2.0 was released in September 2002. Feed, web feed and channel are the other terms that are used to call a RSS document. A RSS document is made up of the full content or the summery along with the metadata (date, author, etc.). Because a standard XML format is used for publications, it allows to be viewed by many applications (even after publishing just once). RSS includes support for XML namespaces. But namespace support is applicable only to the other content available inside RSS 2.0 feed (excluding RSS 2.0 elements). This was done intentionally to preserve the backward compatibility with RSS 1.*. RSS 2.0 was the first web feed to introduce permissions for carrying audio files, which paved the way for the rapid popularity of podcasts. RSS 2.0 introduced the support for enclosures. Because of this, it is the most popular feed type for podcasting. This is evident by the fact that iTunes uses RSS 2.0 on their web site. Copyright of RSS 2.0 was assigned to Harvard, in July 2003. Around the same time, the official RSS Advisory Board (a group that acts as the governing body for the maintenance of the RSS specification) was formed.

What is Atom?

Atom is a more recent web feed format, introduced in June 2003, which was actually developed to overcome some of the limitations (lack of current additions and strictness on backward compatibility) present in RSS 2.0. Atom 1.0 is the latest version and it accommodates a range of content types including text, escaped HTML, well formed XHTML and XML. Atom has separate <summary> and <content> tags. Atom allows entries to link to the feed or standalone entries. Atom can use XML Encryption and XML Digital Signature to encrypt.

What is the difference between RSS and Atom?

RSS only supports text and escaped HTML, but Atom supports a large range of content types (including those two). Unlike RSS, Atom provides two separate tags as <summary> and <content>. RSS is less flexible than Atom, because RSS only recognizes <rss> documents. When it comes to extensibility, although Atom allows the extensions to its namespaces, RSS namespaces are fixed. In addition to standard web encryption techniques used with RSS, XML Encryption and XML Digital Signature can be used with Atom.