Web Design & Development Guide
Screenshot of an RSS feed as seen in
application/rss+xml (Registration Being Prepared)
RSS (which, in its latest format, stands for "Really Simple
Syndication") is a family of
formats used to publish frequently updated content such as
blog entries, news headlines or podcasts. An RSS document, which is called a "feed", "web feed", or
"channel", contains either a summary of content from an associated web site or
the full text. RSS makes it possible for people to keep up with their favorite
web sites in an automated manner that's easier than checking them manually.
RSS content can be read using software
called a "feed reader" or an "aggregator."
The user subscribes to a feed by entering the feed's link into the reader or by
clicking an RSS icon in a browser that initiates the subscription process. The
reader checks the user's subscribed feeds regularly for new content, downloading
any updates that it finds.
The initials "RSS" are used to refer to the following formats:
- Really Simple Syndication (RSS 2.0)
RDF Site Summary (RSS 1.0 and RSS 0.90)
- Rich Site Summary (RSS 0.91)
RSS formats are specified using XML, a generic
specification for the creation of data formats.
Before RSS, several similar formats already existed for syndication, but none
achieved widespread popularity or are still in common use today, as most were
envisioned to work only with a single service. The basic idea of re-structuring
metadata information about web sites has been traced back at least as far as
1995, and the work of Ramanathan V. Guha and others at Apple Computer's Advanced
Technology Group developing the Meta Content Framework (MCF). Other early
work on XML syndication formats, including RDF, took place at Netscape, Userland
Software, and Microsoft.
RDF Site Summary, the first version of RSS, was created by Ramanathan V. Guha
of Netscape in March 1999 for use on the My Netscape portal. This version became known as RSS 0.9.
In July 1999, responding to comments and suggestions, Dan Libby produced a
prototype tentatively named RSS 0.91 (RSS standing for Rich Site Summary),
that simplified the format and incorporated parts of Dave Winer's Scripting News format.
 This they
considered an interim measure, with Libby suggesting an RSS 1.0-like format
through the so-called Futures Document.
In April 2001, in the midst of AOL's acquisition and subsequent restructuring
of Netscape properties, a re-design of the My Netscape portal removed RSS/XML
support. The RSS 0.91 DTD was removed during this re-design, but in response to
feedback, Dan Libby was able to restore the DTD, but not the RSS validator
previously in place. In response to comments within the RSS community at the
time, Lars Marius Garshol, to whom (co?)authorship of the original 0.9 DTD is
sometimes attributed, commented, "What I don't understand is all this fuss over
Netscape removing the DTD. A well-designed RSS tool, whether it validates or
not, would not use the DTD at Netscape's site in any case. There are several
mechanisms which can be used to control the dereferencing of references from XML
documents to their DTDs. These should be used. If not the result will be as
described in the article."
Effectively, this left the format without an owner, just as it was becoming
A working group and mailing list,
RSS-DEV, was set up by various users and XML notables to continue its
development. At the same time, Winer unilaterally posted a modified version of
the RSS 0.91 specification to the Userland website, since it was already in use
in their products. He claimed the RSS 0.91 specification was the property of his
Since neither side had any official claim on the name or the format, arguments
raged whenever either side claimed RSS as its own, creating what became known as
the RSS fork.
RSS-DEV group went on to produce RSS 1.0 in December 2000.
Like RSS 0.9 (but not 0.91) this was based on the RDF specifications, but was
more modular, with many of the terms coming from standard metadata vocabularies
Nineteen days later, Winer released by himself RSS 0.92,
a minor and supposedly compatible set of changes to RSS 0.91 based on the same
proposal. In April 2001, he published a draft of RSS 0.93 which was almost identical to 0.92.
A draft RSS 0.94 surfaced in August, reverting the changes made in 0.93, and
adding a type attribute to the description element.
September 2002, Winer released a final successor to RSS 0.92, known as RSS 2.0
and emphasizing "Really Simple Syndication" as the meaning of the three-letter
abbreviation. The RSS 2.0 spec removed the type attribute added in RSS 0.94 and
allowed people to add extension elements using XML namespaces. Several versions of RSS 2.0 were released, but the version
number of the document model was not changed.
In November 2002, The New York Times began offering its readers the ability
to subscribe to RSS news feeds related to various topics. In January, 2003,
Winer called the New York Times' adoption of RSS the "tipping point" in driving
the RSS format's becoming a de facto standard.
In July 2003, Winer and Userland Software assigned ownership of the RSS 2.0
specification to his then workplace, Harvard's Berkman Center for the Internet &
In January 2005, Sean B. Palmer, Christopher Schmidt, and Cody Woodard produced a preliminary draft of RSS 1.1.
It was intended as a bugfix for 1.0, removing little-used features, simplifying
the syntax and improving the specification based on the more recent RDF
specifications. As of July 2005, RSS 1.1 had amounted to little more than an
In April 2005, Apple Computer released Safari 2.0 with RSS Feed capabilities built in. Safari delivered the ability
to read RSS feeds, and bookmark them, with built-in search features. Safari's
RSS button is a blue rounded rectangle with RSS written inside in white,
displayed defaults to a newspaper icon
In November 2005, Microsoft proposed its Simple Sharing Extensions to RSS.
In December 2005, the Microsoft IE team and Outlook team announced in their
blogs that they will be adopting the feed icon first used in the Mozilla Firefox
effectively making the orange square with white radio waves the industry
standard for both RSS and related formats such as Atom. Also in February 2006,
Opera Software announced they too would add the orange square in their Opera 9 release.
In January 2006, Rogers Cadenhead relaunched an RSS Advisory Board with a view to continuing the development of the RSS
format and resolving ambiguities. In June 2007, the board revised their version
of the specification to confirm that namespaces may extend core elements with
namespace attributes, as Microsoft has done in Internet Explorer 7. In their
view, a difference of interpretation left publishers unsure of whether this was
permitted or forbidden. No press account of the differences between the Winer
spec and the Cadenhead spec for RSS 2.0 is included in this article's
references, though blog searches in May, 2007 found private opinions that the
two specs were very similar.
As noted above, there are several different versions of RSS, falling into two
major branches (RDF and 2.*). The RDF, or RSS 1.* branch includes the following
- RSS 0.90 was the original Netscape RSS version. This RSS was called
RDF Site Summary, but was based on an early working draft of the RDF
standard, and was not compatible with the final RDF Recommendation.
- RSS 1.0 is an open format by the
RSS-DEV Working Group, again standing for RDF Site Summary. RSS
1.0 is an RDF format like RSS 0.90, but not fully compatible with it, since
1.0 is based on the final RDF 1.0 Recommendation.
- RSS 1.1 is also an open format and is intended to update and replace RSS
1.0. The specification is an independent draft not supported or endorsed in
any way by the RSS-Dev Working Group or any other organization.
The RSS 2.* branch (initially UserLand, now Harvard) includes the following
- RSS 0.91 is the simplified RSS version released by Netscape, and also
the version number of the simplified version championed by
Winer from Userland Software. The Netscape version was now called
Rich Site Summary, this was no longer an RDF format, but was relatively
easy to use. It remains the most common RSS variant.
- RSS 0.92 through 0.94 are expansions of the RSS 0.91 format, which are
mostly compatible with each other and with Winer's version of RSS 0.91, but
are not compatible with RSS 0.90. In all Userland RSS 0.9x specifications,
RSS was no longer an acronym.
- RSS 2.0.1 has the internal version number 2.0. RSS 2.0.1 was proclaimed
to be "frozen", but still updated shortly after release without changing the
version number. RSS now stood for Really Simple Syndication. The
major change in this version is an explicit extension mechanism using XML
For the most part, later versions in each branch are backward-compatible with
earlier versions (aside from non-conformant RDF syntax in 0.90), and both
versions include properly documented extension mechanisms using XML Namespaces,
either directly (in the 2.* branch) or through RDF (in the 1.* branch). Most
syndication software supports both branches. Mark Pilgrim's article
"The Myth of RSS Compatibility" discusses RSS version compatibility in more
The extension mechanisms make it possible for each branch to track
innovations in the other. For example, the RSS 2.* branch was the first to
enclosures, making it the current leading choice for
and as of mid-2005 is the format supported for that use by
software; however, an enclosure extension is now available for the RSS 1.*
. Likewise, the RSS 2.* core specification does not support providing
full-text in addition to a synopsis, but the RSS 1.* markup can be (and often
is) used as an extension. There are also several common outside extension
packages available, including a new proposal from Microsoft for use in Internet
The most serious compatibility problem is with HTML markup. Userland's RSS
readerógenerally considered as the reference implementationódid not originally
filter out HTML markup from feeds. As a result, publishers began placing HTML
markup into the titles and descriptions of items in their RSS feeds. This
behavior has become widely expected of readers, to the point of becoming a de
standard, though there is still some inconsistency in how software handles this
markup, particularly in titles. The RSS 2.0 specification was later updated to
include examples of entity-encoded HTML, however all prior plain text usages
In reaction to recognized issues with RSS (and because RSS 2.0 is frozen), a
third group began a new syndication specification,
Atom, in June 2003. Their work was later adopted by the Internet Engineering
Task Force (IETF) leading to the publication of a
4287) for the Atom Format in 2005. Work on the
Atom Publishing Protocol, a standards-based protocol for posting to
publishing tools is ongoing.
The relative benefits of Atom in comparison to the two RSS branches are a
matter of debate within the Web-syndication community. Supporters of Atom claim
that it improves on RSS by relying on standard XML features, by specifying a
payload container that can handle many different kinds of content unambiguously,
and by having a specification maintained by a recognized standards organization.
Critics claim that Atom unnecessarily introduces a third branch of syndication
specifications, further confusing the marketplace.
Atom aims to define both a syntax and a protocol for updating user blogs and
thus goes beyond the simple remit of RSS. While this is appealing to many users,
particularly those in the blogging community, it has been met with resistance in
the professional community (mainly publishers) due to its lack of extensibility.
For a comparison of Atom 1.0 to RSS 2.0 see
Atom Compared to RSS 2.0.
The primary objective of all RSS modules is to extend the basic XML schema
established for more robust syndication of content. This inherently allows for
more diverse, yet standardized, transactions without modifying the core RSS
To accomplish this extension, a tightly controlled vocabulary (in the RSS
world, "module"; in the XML world, "schema") is declared through an XML
namespace to give names to concepts and relationships between those
Some RSS 2.0 modules with established namespaces:
BitTorrent and RSS
The peer-to-peer application BitTorrent has also announced support for RSS. Such feeds (also known as Torrent/RSS-es
or Torrentcasts) will allow client applications to download files
automatically from the moment the RSS reader detects them (also known as
Broadcatching). Most common BitTorrent clients already offer RSS support.
The following is an example of an RSS 1.0 file.
XML.com features a rich mix of information and services
for the XML community.
<image rdf:resource="http://xml.com/universal/images/xml_tiny.gif" />
<rdf:li rdf:resource="http://xml.com/pub/2000/08/09/xslt/xslt.html" />
<rdf:li rdf:resource="http://xml.com/pub/2000/08/09/rdfdb/index.html" />
<textinput rdf:resource="http://search.xml.com" />
<title>Processing Inclusions with XSLT</title>
Processing document inclusions with general XML tools can be
problematic. This article proposes a way of preserving inclusion
information through SAX-based processing.
<title>Putting RDF to Work</title>
Tool and API support for the Resource Description Framework
is slowly coming of age. Edd Dumbill takes a look at RDFDB,
one of the most exciting new RDF toolkits.
<description>Search XML.com's XML collection</description>
The following is an example of an RSS 2.0 file.
<description>Liftoff to Space Exploration.</description>
<pubDate>Tue, 10 Jun 2003 04:00:00 GMT</pubDate>
<lastBuildDate>Tue, 10 Jun 2003 09:41:01 GMT</lastBuildDate>
<generator>Weblog Editor 2.0</generator>
<description>How do Americans get ready to work with Russians aboard the
International Space Station? They take a crash course in culture, language
and protocol at Russia's Star City.</description>
<pubDate>Tue, 03 Jun 2003 09:39:21 GMT</pubDate>
<description>Sky watchers in Europe, Asia, and parts of Alaska and Canada
will experience a partial eclipse of the Sun on Saturday, May 31st.</description>
<pubDate>Fri, 30 May 2003 11:06:42 GMT</pubDate>
<title>The Engine That Does More</title>
<description>Before man travels to Mars, NASA hopes to design new engines
that will let us fly through the Solar System more quickly. The proposed
VASIMR engine would do that.</description>
<pubDate>Tue, 27 May 2003 08:37:32 GMT</pubDate>
<title>Astronauts' Dirty Laundry</title>
<description>Compared to earlier spacecraft, the International Space
Station has many luxuries, but laundry facilities are not one of them.
Instead, astronauts have other options.</description>
<pubDate>Tue, 20 May 2003 08:56:02 GMT</pubDate>
Lash, Alex (1997-10-03).
W3C takes first step toward RDF spec.
My Netscape Network: Quick Start.
Netscape Communications. Archived from
the original on
2000-12-08. Retrieved on 2006-10-31.
Libby, Dan (1999-07-10).
RSS 0.91 Spec, revision 3.
MNN Future Directions.
Netscape Communications. Archived from
the original on
2000-12-04. Retrieved on 2006-10-31.
Andrew King (2003-04-13).
The Evolution of RSS.
RSS 0.91: Copyright and Disclaimer.
RSS-DEV Working Group (2000-12-09).
RDF Site Summary (RSS) 1.0.
RSS 0.92 Specification.
Winer, Dave (2001-04-20).
RSS 0.93 Specification.
RSS 2.0 Specification moves to Berkman.
Berkman Center for the Internet & Society (2003-07-15).
Palmer, Sean B. and Christopher Schmidt (2005-01-23).
RSS 1.1: RDF Site Summary.
Simple Sharing Extensions for RSS and OPML.
T. Hammond, T. Hannay, and B. Lund, "The Role of RSS in Science
Publishing," D-Lib Magazine, vol. 10, pp. 1082-9873, 2004.