Every action made on the platform generates an Activity, which is a short, storified representation of it.
Here’s an example : A Player who earns a Badge will generate an activity, which relates the story “Player XXX earned the YYY badge”
Those activities are structured, so you can request them in many ways, and get consistent results in the form of Feeds. Those feeds can be very focused (The posts from a Facebook Wall) or very diverse (A custom feed of Everything for a client, plus all of the Posts, Badge wins and Shares of my Friends)
The flexibility of this systme allows you to get rich, realtime engaging news feeds for almost any situation.