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 by adding the feed resource address to a news aggregator client (also called a feed reader or a news reader). Users typically subscribe to a feed by manually entering the URL of a feed or clicking a link in a web browser or by dragging the link from the web browser to the aggregator, thus "RSS and Atom files provide news updates from a website in a simple form for your computer."
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. As web feeds are designed to be machine-readable rather than human-readable they can also be used to automatically transfer information from one website to another without any human intervention.
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 search results.
Common web feed formats are:
Although RSS formats have evolved since March 1999, the RSS icon ("") first gained widespread use between 2005 and 2006. The feed icon indicates that a web feed is available. The original icon was created by Stephen Horlander, a designer at Mozilla. With the prevalence of JSON in Web APIs, a further format, JSON Feed, was defined in 2017.
Comparison to email subscriptions
Web feeds have some advantages compared to receiving frequently published content via an email:
- Users do not disclose their email address when subscribing to a feed and so are not increasing their exposure to threats associated with email: spam, viruses, phishing, and identity theft.
- Users do not have to send an unsubscribe request to stop receiving news. They simply remove the feed from their aggregator.
- The feed items are automatically sorted in that each feed URL has its own sets of entries (unlike an email box where messages must be sorted by user-defined rules and pattern matching).
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- See Wikipedia:Syndication on how various aspects of Wikipedia can be monitored with RSS or Atom feeds.