Screens are program components with which an ABAP program can communicate with users through SAP GUI.
This section describes the direct programming and use of screens in ABAP programs. You can do this in function groups, module pools, and executable programs.
This section explains how to pass data between user dialogs and ABAP programs, how to define user dialogs within and outside your programs, and how to process user input.
The properties described in the General Screens section apply, in principle, for all screens. For general screens, you need to define or program all properties yourself. For selection screens, the ABAP runtime environment largely takes care of the definition and flow control. Messages are also closely linked with the screen technology and are displayed on screens.

Another type of
screen-based user interface are classical lists most of which are, however, no
longer in use today. See:
Obsolete
Techniques..