Overview of Atom feeds

A web feed, sometimes just called a "feed", is a series of related items that a content provider publishes on the Internet. An Atom feed is a web feed that uses the Atom Syndication Format and the Atom Publishing Protocol.

Atom comprises an XML-based format that describes an Atom feed and the items of information in it, and a protocol for publishing and editing Atom feeds. This format and protocol are described in two Internet Society and IETF (Internet Engineering Task Force) Request for Comments documents (known as RFCs): Content providers often deliver web feeds in an earlier format called RSS (Really Simple Syndication). CICS supports Atom, but does not support RSS.

The items of information that make up an Atom feed are known as Atom entries. A content provider publishes, or "syndicates", an Atom feed by making it available through a URL on the Internet and updating it with new items. Web pages can display the items in the Atom feed, and web users can obtain the items from the feed using a feed reader or web browser. An Atom feed might be used as part of a mashup, which is a web application that merges content from a number of data sources so that users can experience and understand the data in a new way. In a mashup, the data from the Atom feed can be handled by a widget, which is a script application that runs in a web page.

The Atom Publishing Protocol specifies the way that users can add, delete, edit, or view individual Atom entries in an Atom feed by making HTTP requests to a server that stores the entries. A GET request retrieves an entry for viewing, a POST request adds a complete new entry, a PUT request edits an existing entry, and a DELETE request deletes an entry. The server handles the requested changes in an appropriate way and responds to the user's client with confirmation of the changes.