One of the application component type is called '''Activity''' and provides a screen for the user to interact with.
Activity is that part of the application that provides a screen for the user to interact with. The activity object could be created from a subclass of the [http://d.android.com/reference/android/app/Activity.html Activity] classor one of its subclasses. Based of the user input on the activity screen, the operating system calls into your class some important methods. The figure from [http://d.android.com/guide/topics/fundamentals/activities.html this source] illustrates the life cycle of an android activity component.
