RSS is a family of XML file formats for Web syndication used by (among other things) news websites and weblogs. The abbreviation is used to refer to the following standards:
Rich Site Summary (RSS 0.91)
RDF Site Summary (RSS 0.9 and 1.0)
Really Simple Syndication (RSS 2.0.0)
The technology of RSS allows Internet users to subscribe to websites that have provided RSS feeds; these are typically sites that change or add content regularly. To use this technology, site owners create or obtain specialized software (such as a content management system) which, in the machine-readable XML format, presents new articles in a list, giving a line or two of each article and a link to the full article or post. Unlike subscriptions to many printed newspapers and magazines, most RSS subscriptions are free.
The RSS formats provide web content or summaries of web content together with links to the full versions of the content, and other meta-data. This information is delivered as an XML file called an RSS feed, webfeed, RSS stream, or RSS channel. In addition to facilitating syndication, RSS allows a website's frequent readers to track updates on the site using an aggregator.
RSS is widely used by the weblog community to share the latest entries' headlines or their full text, and even attached multimedia files. (See podcasting, vodcasting, broadcatching, photocasting, picturecasting, screencasting, Vloging, and MP3 blogs.) In mid 2000, use of RSS spread to many major news organizations, including Reuters, CNN, and the BBC, until under various usage agreements, providers allow other websites to incorporate their "syndicated" headline or headline-and-short-summary feeds. RSS is now used for many purposes, including marketing, bug-reports, or any other activity involving periodic updates or publications.
A program known as a feed reader or aggregator can check RSS-enabled webpages on behalf of a user and display any updated articles that it finds. It is now common to find RSS feeds on major Web sites, as well as many smaller ones.
Client-side readers and aggregators are typically constructed as standalone programs or extensions to existing programs like web browsers. Such programs are available for various operating systems. See list of news aggregators.
Web-based feed readers and news aggregators require no software installation and make the user's "feeds" available on any computer with Web access. Some aggregators syndicate (combine) RSS feeds into new feeds, e.g. take all football related items from several sports feeds and provide a new football feed. There are also search engines for content published via RSS feeds like Feedster, Blogdigger or Plazoo.
On Web pages, RSS feeds are typically linked with an orange rectangle optionally with the letters XML or RSS .
An aggregator or news aggregator is a type of software that collects syndicated Web content, such as RSS and other XML feeds from weblogs, podcasts, vlogs, and mainstream mass media websites.
Aggregators improve upon the time and effort needed to regularly check websites of interest for updates, creating a unique information space or "personal newspaper." An aggregator is able to subscribe to a feed, check for new content at user-determined intervals, and retrieve the content. The content is sometimes described as being "pulled" to the subscriber, as opposed to "pushed" with email or IM. Unlike recipients of some "pushed" information, the aggregator user can easily unsubscribe from a feed.
Aggregator features are gradually being built into portal sites, such as My Yahoo!, Web browsers, such as Mozilla Firefox, Safari, Opera, e-mail programs like Microsoft Outlook, and other applications, including Apple's iTunes, which serves as a podcast aggregator.
The aggregator provides a consolidated view of the content in a single browser display or desktop application. Such applications are also referred to as RSS readers, feed readers, feed aggregators or news readers, although in Internet communication, the latter term was first used for programs that read Usenet newsgroups.
A website may incorporate aggregator features by republishing syndicated content on one or more of its pages. Aggregator features also may be incorporated in other client software, including Web browsers, e-mail clients, weblog creation programs, or media player programs. Devices such as mobile phones or Tivo video recorders (already aggregating television programs) may incorporate XML aggregators.
The syndicated content an aggregator will interpret is usually in RSS or other XML-based data, such as RDF or Atom formats.