This document discusses developing apps for the Windows Phone Marketplace. It covers why developers should create apps for Windows Phone, what types of apps are good fits for the platform, and how to submit an app to the marketplace. Specifically, it notes that over 30% of mobile device users in the UK use apps, representing a potential revenue opportunity. It provides resources for the app development tools and outlines the five step process for submitting an app, including ensuring it meets content, application, and submission policies. Developers are encouraged to create unique apps that solve specific problems or reinvent concepts to stand out amongst competitors.