The document discusses building desktop applications with Adobe AIR using web technologies like PHP, HTML, and JavaScript. AIR allows developers to create desktop apps using these web technologies by packaging them into an executable that can be run on Windows, Mac or Linux systems. It works by embedding a Flash Player with special AIR APIs and a HTMLLoader control that uses the same WebKit engine as Safari to display HTML content. Developers can build AIR apps using Flex, Flash or plain HTML/JS/CSS and package them with an application descriptor file and initial content file.