In this installment of the Android Development Essential Training series, David Gassner explains how to build mobile apps for Android that support multiple screens and devices. He begins by discussing Android market fragmentation, and then explains how to set the minimum SDK level and check the current device's screen size programmatically. Next, he covers how to work with multiple screens, explaining how to create alternative resource directories that the app framework can recognize and use to ensure that particular elements—such as string values, dimensions, and graphics—appear the way you want them to on different devices. To wrap up, David shows how to work with fragments to create dynamic UIs.