Описание тега android-ui
In an Android application, the user interface is built using `View` and `ViewGroup` objects. There are many types of views and view groups, each of which is a descendant of the View class.
For more information please visit:http://developer.android.com/guide/topics/ui/index.html
All user interface elements in an Android app are built using View and ViewGroup objects. A View is an object that draws something on the screen that the user can interact with. A ViewGroup is an object that holds other View (and ViewGroup) objects in order to define the layout of the interface.