An aggregator or news aggregator is a type of software that retrieves syndicated Web content that is supplied in the form of a web feed (RSS, Atom and other XML formats), and that are published by weblogs, podcasts, vlogs, and mainstream mass media websites.

What do aggregators do?

Aggregators reduce the time and effort needed to regularly check websites of interest for updates, creating a unique information space or "personal newspaper." An aggregator is able to subscribe to a feed, check for new content at user-determined intervals, and retrieve the content. The content is sometimes described as being "pulled" to the subscriber, as opposed to "pushed" with email or IM. Unlike recipients of some "pushed" information, the aggregator user can easily unsubscribe from a feed.

Aggregator features are gradually being built into portal sites such as My Yahoo! and Google, Web browsers such as Mozilla Firefox, Safari, Opera, e-mail programs like Mozilla Thunderbird, and other applications, including Apple's iTunes, which serves as a podcast aggregator.

The aggregator provides a consolidated view of the content in a single browser display or desktop application. Such applications are also referred to as RSS readers, feed readers, feed aggregators or news readers, although in Internet communication, the latter term was first used for programs that read Usenet newsgroups.