A Drawable resource providing a graphical representation of its associated item. Use with the application tag (to supply a default icon for all application components), or with the activity, receiver, service, or instrumentation tag (to supply a specific icon for that component). It may also be used with the intent-filter tag to supply an icon to show to the user when an activity is being selected based on a particular Intent.

The given icon will be used to display to the user a graphical representation of its associated component; for example, as the icon for main activity that is displayed in the launcher. This must be a reference to a Drawable resource containing the image definition.

Must be a reference to another resource, in the form "@[+][package:]type:name" or to a theme attribute in the form "?[package:][type:]name".

[Android Documentation]