On the World Wide Web, a web feed (or news feed) is a data format used for providing users with frequently updated content. Content distributors syndicate a web feed, thereby allowing users to subscribe a channel to it. Making a collection of web feeds accessible in one spot is known as aggregation, which is performed by a news aggregator. A web feed is also sometimes referred to as a syndicated feed.

A typical scenario of web-feed use might involve the following: a content provider publishes a feed link on its site which end users can register with an aggregator program (also called a feed reader or a news reader) running on their own machines; doing this is usually as simple as dragging the link from the web browser to the aggregator. When instructed, the aggregator asks all the servers in its feed list if they have new content; if so, the aggregator either makes a note of the new content or downloads it. One can schedule aggregators to check for new content periodically.

Web feeds exemplify pull technology, although they may appear to push content to the user.

The kinds of content delivered by a web feed are typically HTML (webpage content) or links to webpages and other kinds of digital media. Often when websites provide web feeds to notify users of content updates, they only include summaries in the web feed rather than the full content itself.

Many news websites, weblogs, schools, and podcasters operate web feeds.

Work Web feeds have some advantages compared to receiving frequently published content via an email:

In its explanation "What is a web feed?", the publishing group of Nature describes two benefits of web feeds:

Usually a web feed is made available by the same entity that created the content. Typically the feed comes from the same place as the website. Not all websites, however, provide a feed. Sometimes third parties will read the website and create a feed for it by scraping it. Scraping is controversial since it distributes the content in a manner that was not chosen by the authors and may bypass web advertisements.

A web feed is a document (often XML-based) whose discrete content items include web links to the source of the content. News websites and blogs are common sources for web feeds, but feeds are also used to deliver structured information ranging from weather data to top-ten lists of hit tunes to search results. The two main web feed formats are RSS and Atom.

"Publishing a feed" and "syndication" are two of the more common terms used to describe making a feed available for an information source such as a blog. Web feed content, like syndicated print newspaper features or broadcast programs, may be shared and republished by other websites. (For that reason one popular definition of RSS is Really Simple Syndication.)

Feeds are more often subscribed to directly by users with aggregators or feed readers which combine the contents of multiple web feeds for display on a single screen or series of screens. Some modern web browsers incorporate aggregator features. Users typically subscribe to a feed by manually entering the URL of a feed or clicking a link in a web browser.

Web feeds are designed to be machine-readable rather than human-readable, which tends to be a source of confusion when people first encounter web feeds. This means that web feeds can also be used to automatically transfer information from one website to another without any human intervention.

The term RSS is often used to refer to web feeds or web syndication in general, although not all feed formats are RSS. The Blogspace description of using web feeds in an aggregator, for example, is headlined "RSS info" and "RSS readers" even though its first sentence makes clear the inclusion of the Atom format: "RSS and Atom files provide news updates from a website in a simple form for your computer."^[1]

The Feed icon is for indicating that a web feed is available on a web page. It was originally invented for the use of RSS, but it is also common for Atom and other web feeds now. The icon is normally orange, with hex code #FA9B39. The original icon was created by Stephen Horlander, a designer at Mozilla.

The icon is used in aggregators, web browsers address bar to indicate availabity of a web feed, as well as on web pages to subscribe directly.

RSS formats are specified using XML, a generic specification for the creation of data formats. Although RSS formats have evolved since March 1999,^[2] the RSS icon ("[[INLINE_IMAGE|//upload.wikimedia.org/wikipedia/en/thumb/4/43/Feed-icon.svg/16px-Feed-icon.svg.png|//upload.wikimedia.org/wikipedia/en/thumb/4/43/Feed-icon.svg/24px-Feed-icon.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/43/Feed-icon.svg/32px-Feed-icon.svg.png 2x|Feed-icon.svg|h16|w16]]") first gained widespread use between 2005 and 2006.^[3]

Dave 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.^[4] A few months later, UserLand filed a U.S. trademark registration for RSS, but failed to respond to a USPTO trademark examiner's request and the request was rejected in December 2001.^[5]

The RSS-DEV Working Group, a project whose members included Guha and representatives of O'Reilly Media and Moreover, produced RSS 1.0 in December 2000.^[6] This new version, which reclaimed the name RDF Site Summary from RSS 0.9, reintroduced support for RDF and added XML namespaces support, adopting elements from standard metadata vocabularies such as Dublin Core.

In December 2000, Winer released RSS 0.92^[7] 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 spark podcasting. He also released drafts of RSS 0.93 and RSS 0.94 that were subsequently withdrawn.^[8]

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 the type attribute added in the RSS 0.94 draft and added support for namespaces.

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 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.^[9] 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 as RFC 4287 ^[20] .

In July 2003, Winer and UserLand Software assigned the copyright of the RSS 2.0 specification to Harvard's Berkman Center for Internet & Society, where he had just begun a term as a visiting fellow.^[10] At the same time, Winer launched the RSS Advisory Board with Brent Simmons and Jon Udell, a group whose purpose was to maintain and publish the specification and answer questions about the format.^[11]

In December 2005, the Microsoft Internet Explorer team^[12] and Outlook team^[13] announced on their blogs that they were adopting the feed icon first used in the Mozilla Firefox browser [[INLINE_IMAGE|//upload.wikimedia.org/wikipedia/en/thumb/4/43/Feed-icon.svg/16px-Feed-icon.svg.png|//upload.wikimedia.org/wikipedia/en/thumb/4/43/Feed-icon.svg/24px-Feed-icon.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/43/Feed-icon.svg/32px-Feed-icon.svg.png 2x|Feed-icon.svg|h16|w16]], created by Stephen Horlander, a Mozilla Designer. A few months later, Opera Software followed suit. 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.