The feed plugin allows you to offer an XML file representings you latest public posts. We currently support two formats: Atom 1.0 and RSS 2.0.
Feeds may include the entire content of your public posts, however, by default we compute a teaser of just 300 or so words. The size of the teaser can be defined for each feed. The settings also determines how many entries are added to each feed and when a post times out and should be removed from the feed.
The feeds get updated regularly and should be up to date within the amount of time it takes to run you main backend system. By default this is setup to run once every five minutes.
By default feeds are created for your entire website. If you are a small company, that usually is way more than enough. If you have many writers who post daily, you may want to consider creating separate feeds using various criteria such as the author who writes the posts, the category the posts go in, etc.
Note: As of 2012 or so, the craze over feeds in general dropped dramatically. There are still many tools (browsers, mail systems, standalone applications) that can be used to follow RSS and Atom feeds, although it is not unlikely to continue to fall out of scope.