The document discusses Ionic, an open source toolkit for building cross-platform mobile apps with web technologies. Ionic allows developers to build apps that look and feel like native iOS, Android, and Windows apps while sharing code across platforms. It includes UI elements and interactions that mimic each platform as well as tools to package a website into a native mobile app and access device features through its native bridge. Examples are given of apps built with Ionic including a crypto balance checker and data collection app.