Multi-platform advertising has become a global phenomenon. It is also widely known as cross-device, cross-media, cross-platform, cross-touchpoints, and cross-channel advertising. This book chapter provides an overview of multi-platform advertising in terms of its consumer platform usage behavior, global diffusion, emerging metrics, opportunities and challenges as perceived by major players, regulatory concerns, and technological developments. This book chapter offers the up-dated contextual information to allow readers of this edited volume to comprehend better the phenomenon of multi-platform advertising around the world.