This document provides an introduction to Vaadin, a Java-based web application framework. It highlights key features of Vaadin 7 including rich UI components, support for multiple browsers and devices, built-in themes, and an architecture that separates the user interface from the data model and server communication. The document also summarizes new features in Vaadin 7 such as a windowing API, Sass support, redesign forms, RPC and state handling, and server push capabilities.