Web feed

On the World Wide Web, a web 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. 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 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.

Technical definition

A web feed is a document 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: