Atom is an XML-based document format that describes lists of related information known as "feeds". Feeds are composed of a number of items, known as "entries", each with an extensible set of attached metadata. For example, each entry has a title.
The primary use case that Atom addresses is the syndication of Web content such as weblogs and news headlines to WEB sites as well as directly to user agents.
The name Atom applies to a pair of related standards and was developed as an alternative to RSS.
The Atom Syndication Format and the Atom Publishing Protocol (AtomPub or APP) is a simple HTTP-based protocol for creating and updating web resources.
Web feeds allow software programs to check for updates published on a website. To provide a web feed, a site owner may use specialised software (such as a content management system) that publishes a list (or "feed") of recent articles or content in a standardised, machine-readable format. The feed can then be downloaded by programs that use it, like websites that syndicate content from the feed, or by feed reader programs that allow Internet users to subscribe to feeds and view their content.
A feed contains entries, which may be headlines, full-text articles, excerpts, summaries, and/or links to content on a website, along with various metadata.