The document discusses DOM events. It begins by explaining that any web page, regardless of how dynamic or app-like, is essentially a document. It then covers topics including the DOM and BOM, how to attach and detach DOM events, DOM event flow, the event object, and event delegation. The DOM represents the document as a tree structure that can be programmatically accessed and updated, while the BOM provides an interface between JavaScript and the browser. Events are important for making the DOM interactive.