Atom is the new syndication format for the Web which has been designed to replace RSS. Atom follows the same idea of syndication as Web-Based Publishing of items. In addition to the syndication format of Atom, which is similar to RSS, Atom also defines the Atom Publishing Protocol (APP), which extends the interaction of users with Atom feeds from a read-only model to a more dynamic interaction, including the posting of new items to a feed. Atom relies heavily on XML Technologies and APP is a RESTful protocol using the Atom format and defining rules for interacting with Atom feeds.

The most useful part of Atom is its extensibility. Atom specifies the basic format for feed items and the protocol how to interact with feeds. Applications built on top of Atom and APP can use extensions to publish and manage more sophisticated information items, one popular example for this is GeoRSS for encoding Geolocation information in RSS and Atom feeds. Using GeoRSS-enabled Atom feeds, it is possible to publish a stream of localized resources (for example tracking a person's or object's movements) rather than just abstract items.