This document provides an overview of Material Design and the Android M preview. It discusses the goals of Material Design including a unified experience across platforms. It outlines several principles of Material Design such as using motion to provide meaning and responding to user interactions. It also provides examples of style guidelines for color, iconography, imagery, and typography. Additionally, it covers several features from the Android M preview like app permissions, biometric security, Google Now on Tap and Chrome integration. The document is intended to introduce developers to Material Design and the updated features in the Android M software development kit preview.