RSS (RDF Site Summary orReally Simple Syndication)[2] is aweb feed[3] that allows users and applications to access updates to websites in astandardized, computer-readable format. Subscribing to RSS feeds can allow a user to keep track of many different websites in a singlenews aggregator, which constantly monitors sites for new content, removing the need for the user to manually check them. News aggregators (or "RSS readers") can be built into abrowser, installed on adesktop computer, or installed on amobile device.[4]
Websites usually use RSS feeds to publish frequently updated information, such asblog entries, news headlines, episodes of audio and video series, or for distributingpodcasts. An RSS document (called "feed", "web feed",[5] or "channel") includes full or summarized text, andmetadata, like publishing date and author's name. RSS formats are specified using a genericXML file.[4]
Although RSS formats have evolved from as early as March 1999,[6] it was between 2005 and 2006 when RSS gained widespread use, and the ("") icon was decided upon by several major web browsers.[7] RSS feed data is presented to users using software called a news aggregator and the passing of content is calledweb syndication. Users subscribe to feeds either by entering a feed'sURI into the reader or by clicking on the browser'sfeed icon. The RSS reader checks the user's feeds regularly for new information and can automatically download it, if that function is enabled.
History
This section needs to beupdated. Please help update this article to reflect recent events or newly available information.(October 2013)
RDF Site Summary, the first version of RSS, was created byDan Libby, Ramanathan V. Guha, andEckart Walther atNetscape.[9] It was released in March 1999 for use on the My.Netscape.Com portal.[10] This version became known as RSS 0.9.[6] In July 1999, Dan Libby of Netscape produced a new version, RSS 0.91,[3] which simplified the format by removing RDF elements and incorporating elements fromDave Winer's news syndication format.[11] Libby also renamed the format from RDF to RSSRich Site Summary and outlined further development of the format in a "futures document".[12]
This would be Netscape's last participation in RSS development for eight years. As RSS was being embraced by web publishers who wanted their feeds to be used on My.Netscape.Com and other early RSS portals, Netscape dropped RSS support from My.Netscape.Com in April 2001 during new ownerAOL's restructuring of the company, also removing documentation and tools that supported the format.[13]
Two parties emerged to fill the void, with neither Netscape's help nor approval: TheRSS-DEV Working Group and Dave Winer, whoseUserLand Software had published some of the first publishing tools outside Netscape that could read and write RSS.
Winer published a modified version of the RSS 0.91 specification on the UserLand website, covering how it was being used in his company's products, and claimed copyright to the document.[14] A few months later, UserLand filed a U.S. trademark registration for RSS, but failed to respond to aUSPTO trademark examiner's request and the request was rejected in December 2001.[15]
The RSS-DEV Working Group, a project whose members includedAaron Swartz,[16] Guha and representatives ofO'Reilly Media andMoreover, produced RSS 1.0 in December 2000.[17] This new version, which reclaimed the name RDF Site Summary from RSS 0.9, reintroduced support for RDF and addedXML namespaces support, adopting elements from standard metadata vocabularies such asDublin Core.
In December 2000, Winer released RSS 0.92[18]a minor set of changes aside from the introduction of the enclosure element, which permitted audio files to be carried in RSS feeds and helped sparkpodcasting. He also released drafts of RSS 0.93 and RSS 0.94 that were subsequently withdrawn.[19]
In September 2002, Winer released a major new version of the format, RSS 2.0, that redubbed its initials Really Simple Syndication. RSS 2.0 removed thetype attribute added in the RSS 0.94 draft and added support for namespaces. To preserve backward compatibility with RSS 0.92, namespace support applies only to other content included within an RSS 2.0 feed, not the RSS 2.0 elements themselves.[20] (Although other standards such asAtom attempt to correct this limitation, RSS feeds are not aggregated with other content often enough to shift the popularity from RSS to other formats having full namespace support.)
Because neither Winer nor the RSS-DEV Working Group had Netscape's involvement, they could not make an official claim on the RSS name or format. This has fueled ongoing controversy[specify] in the syndication development community as to which entity was the proper publisher of RSS.
One product of that contentious debate was the creation of an alternative syndication format, Atom, that began in June 2003.[21] The Atom syndication format, whose creation was in part motivated by a desire to get a clean start free of the issues surrounding RSS, has been adopted asIETF Proposed StandardRFC4287.
In July 2003, Winer and UserLand Software assigned the copyright of the RSS 2.0 specification to Harvard'sBerkman Klein Center for Internet & Society, where he had just begun a term as a visiting fellow.[22] At the same time, Winer launched theRSS Advisory Board withBrent Simmons andJon Udell, a group whose purpose was to maintain and publish the specification and answer questions about the format.[23]
In December 2005, the Microsoft Internet Explorer team[7] andMicrosoft Outlook team[25] announced on their blogs that they were adopting Firefox's RSS icon. In February 2006,Opera Software followed suit.[26] This effectively made the orange square with white radio waves the industry standard for RSS and Atom feeds, replacing the large variety of icons and text that had been used previously to identify syndication data.
In January 2006,Rogers Cadenhead relaunched the RSS Advisory Board without Dave Winer's participation, with a stated desire to continue the development of the RSS format and resolve 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. According to their view, a difference of interpretation left publishers unsure of whether this was permitted or forbidden.
Example
RSS isXML-formatted plain text. The RSS format itself is relatively easy to read both by automated processes and by humans alike. An example feed could have contents such as the following:
User interface of an RSS feed reader on a desktop computer
When retrieved, RSS reading software could use the XML structure to present a neat display to the end users. There are various news aggregator software for desktop and mobile devices, but RSS can also be built-in insideweb browsers oremail clients likeMozilla Thunderbird.
Variants
There are several different versions of RSS, falling into two major branches (RDF and 2.*).
The RDF (or RSS 1.*) branch includes the following versions:
RSS 0.90 was the original Netscape RSS version. This RSS was calledRDF 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 forRDF 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 versions:
RSS 0.91 is the simplified RSS version released by Netscape, and also the version number of the simplified version originally championed by Dave Winer from Userland Software. The Netscape version was now calledRich Site Summary; this was no longer an RDF format, but was relatively easy to use.
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.
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 forReally Simple Syndication. The major change in this version is an explicit extension mechanism using XML namespaces.[27]
Later versions in each branch arebackward-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. "The Myth of RSS Compatibility", an article written in 2004 by RSS critic andAtom advocateMark Pilgrim, discusses RSS version compatibility issues in more detail.
The extension mechanisms make it possible for each branch to copy innovations in the other. For example, the RSS 2.* branch was the first to supportenclosures, making it the current leading choice for podcasting, and as of 2005[update] is the format supported for that use byiTunes and other podcasting software; however, an enclosure extension is now available for the RSS 1.* branch, mod_enclosure. 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, e.g. one fromMicrosoft for use inInternet Explorer 7.
The most serious compatibility problem is with HTML markup. Userland's RSS reader—generally considered as the reference implementation—did not originally filter outHTML 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 expected of readers, to the point of becoming ade facto standard.[28] 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 remain valid.
As of January 2007[update], tracking data from www.syndic8.com indicates that the three main versions of RSS in current use are 0.91, 1.0, and 2.0, constituting 13%, 17%, and 67% of worldwide RSS usage, respectively.[29] These figures, however, do not include usage of the rival web feed format Atom. As of August 2008[update], the syndic8.com website is indexing 546,069 total feeds, of which 86,496 (16%) were some dialect of Atom and 438,102 were some dialect of RSS.[30]
Modules
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 specification.
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 concepts.
Some RSS 2.0 modules with established namespaces are:
Although the number of items in an RSS channel is theoretically unlimited, somenews aggregators do not support RSS files larger than 150KB.[citation needed] For example, applications that rely on the Common Feed List ofWindows might handle such files as if they were corrupt, and not open them.Interoperability can be maximized by keeping the file size under this limit.
Podcasts are distributed using RSS. To listen to a podcast, a user adds the RSS feed to their podcast client, and the client can then list available episodes and download or stream them for listening or viewing. To be included in a podcast directory the feed must for each episode provide a title, description, artwork, category, language, and explicit rating. There are some services that specifically indexes and is asearch engine for podcasts.[31]
Some services deliver RSS to an email inbox, sending updates from user's personal selection and schedules. Examples of such services includeIFTTT,Zapier and others.[32] Conversely, some services deliver email to RSS readers.[33] Further services like e.g.Gmane allow to subscribe to feeds viaNNTP.
Both RSS andAtom are widely supported and are compatible with all major consumer feed readers. RSS gained wider use because of early feed reader support. Technically, Atom has several advantages: less restrictive licensing,IANA-registeredMIME type, XML namespace,URI support,RELAX NG support.[35]
The following table shows RSS elements alongside Atom elements where they are equivalent.
Note: theasterisk character (*) indicates that an element must be provided (Atom elements "author" and "link" are only required under certain conditions).
Several major sites such asFacebook andTwitter previously offered RSS feeds, but have reduced or removed support. Additionally, widely used readers such asShiira, FeedDemon, and particularlyGoogle Reader, have all been discontinued as of 2013, citing declining popularity in RSS.[36] RSS support was removed inOS X Mountain Lion's versions ofMail andSafari, although the features were partially restored in Safari 8.[37][38] Mozilla removed RSS support fromMozilla Firefox version 64.0, joiningGoogle Chrome andMicrosoft Edge [Legacy] which do not include RSS support.[39][40]
Since the late 2010s, however, there has been an uptick in RSS interest again. In 2018,Wired published an article named "It's Time for an RSS Revival", citing that RSS gives more control over content compared to algorithms and trackers from social media sites. At that time,Feedly was the most popular RSS reader.[41]Microsoft Edge (New) onWindows andGoogle Chrome on Android added the ability to follow RSS feeds as of 2021.[42][43][44]
^Powers 2003, p. 10: "Another very common use of RDF/XML is in a version of RSS called RSS 1.0 or RDF/RSS. The meaning of the RSS abbreviation has changed over the years, but the basic premise behind it is to provide an XML-formatted feed consisting of an abstract of content and a link to a document containing the full content. When Netscape originally created the first implementation of an RSS specification, RSS stood for RDF Site Summary, and the plan was to use RDF/XML. When the company released, instead, a non-RDF XML version of the specification, RSS stood for Rich Site Summary. Recently, there has been increased activity with RSS, and two paths are emerging: one considers RSS to stand for Really Simple Syndication, a simple XML solution (promoted as RSS 2.0 by Dave Winer at Userland), and one returns RSS to its original roots of RDF Site Summary (RSS 1.0 by the RSS 1.0 Development group)."
^Winer, Dave (December 25, 2000)."RSS 0.92 Specification". UserLand Software. Archived fromthe original on January 31, 2011. RetrievedOctober 31, 2006.
^Winer, Dave (April 20, 2001)."RSS 0.93 Specification". UserLand Software. Archived fromthe original on November 2, 2006. RetrievedOctober 31, 2006.
^Festa, Paul (August 4, 2003)."Dispute exposes bitter power struggle behind Web logs". news.cnet.com.Archived from the original on August 6, 2009. RetrievedAugust 6, 2008.The conflict centers on something called Really Simple Syndication (RSS), a technology widely used to syndicate blogs and other Web content. The dispute pits Harvard Law School fellow Dave Winer, the blogging pioneer who is the key gatekeeper of RSS, against advocates of a different format.
^Hölzle, Urs (March 13, 2013)."A second spring of cleaning". googleblog.blogspot.com.Archived from the original on March 14, 2013. RetrievedMarch 14, 2013.
