The document discusses the importance of having a mobile-friendly website. It provides reasons to go mobile like reaching a larger audience as there are over 4.6 billion mobile phones worldwide. A mobile site allows crucial content and features to be optimized for smaller screens compared to full websites. The document recommends tools to build a mobile site and essential design features like vertical navigation and prioritizing key content. Examples are given of how sites like Kayak, Dell, and Def Jam adapted their designs for mobile.