The user interface of an operating system is the portion of the program with which users interact.
The user interface can be
A command-line interface requires a user to type the desired response at a prompt using a special command language.
To be an effective user of any command-line software, you must memorize its commands and their exact syntax-no easy task.
A menu-driven interface allows the user to select commands from a list (menu) using the keyboard or a pointing device such as a mouse.
A graphical user interface (GUI):
The trend is away from text-based, command-line interfaces to user-friendly, graphics-oriented environment called a graphical user interface (GUI).
Graphical user interfaces rely on graphics-based software.
Graphic-based software permits the integration of text with high-resolution graphic
image, called icons.
GUI users interact with the operating system and other software packages by using a pointing device and a keyboard to issue commands.
Rather than enter a command directly, the user chooses from options displayed on the screen.
The equivalent of a syntax-sensitive operating system command is entered by pointing to and choosing one or more options from menu or by pointing to and choosing a graphics image, called an icon.
Typically GUI includes some or all of the following parts:
-Icons, which are graphical images that represent items, such as files and directories.
-Agraphical pointer, which is controlled by a pointing device (mouse), to select icons and
commands and move on-screen items.
-On-screen pull-down menus that appear or disappear, controlled by the pointing device.
-Windows that enclose applications or objects on the screen.
GUIs have effectively eliminated the need for users to memorize and enter cumbersome commands.