A RSS (or ATOM ) feed is a web page designed to be read by programs not people. It is used to publish a list of dated items such as blog posts, recent changes or news. Feeds are updated when new items are added to the list. Each item is usually a summary with a link to full item on a website but can also contain links to media such as MP3 files (which turns the feed into a podcast).

RS feeds allow syndication as sites can easily present information available from other sites. They really caught on with the rise of blogs as they provide an easy way to see when new posts are made by the blogger.

A program called an reader or aggregator is used to subscribe to feeds and every now an then will check if those feeds have been updated since it last looked and lets you know of any changes. You usually get a list of the items with summaries and can drill down to the full articles. Many progams act as feed readers including installed programs such thunderbird, firefox and web based readers such as Bloglines (see MyFeeds tab).

Some aggregator collect a number of feeds and mix them into a single list, usually a web page rather than another RSS feed. For example it provides a blog that shows all the items from a number of other blogs. See the PlanetUbuntu Linux blog aggregator for an example. The BlogBridge program and web service combination looks good and has flexible grouping called guides (see this intro).

• Information on OATS feeds