"Really Simple Syndication": a format for syndicating many types of content, including blog entries, torrent files, video clips on news-like sites; specifically frequently updated content on a Web site, and is also known as a type of "feed" or "aggregator". An RSS feed can contain a summary of content or the full text, and makes it easier for people to keep up to date with sites they like in an automated manner (much like e-mail).
The content of the feed can be read by using software called an RSS or Feed reader. Feed readers display hyperlinks, and include other metadata (information about information) that helps people decide whether they want to read more, follow a link, or move on.
The original intent of RSS is to make information come to you (via the feed reader) instead of you going out to look for it (via the Web).
Programs called news aggregators permit users to view many feeds at once, providing 'push' content constantly. See Category:Feeds for Codex resources about bringing RSS feeds into WordPress. See also RDF Site Summary.