In Android, what you see is activity. You interact with Android application through activity. Usually application has more than one activity that are connected each other. In other words, what you see in an Android device is an activity
Android is now one of the most popular smartphone/mobile operating system in the world. This tutorial will help you on creating your first android application (Hello World application) using Eclipse IDE and Android Development Tools (ADT) and also Android Virtual Device (AVD) or your real android device to run the application.