You have learned to write simple C# programs that accept input from
a user at the console and produce output at the command line. Th e
environment the user sees is a program’s interface; unfortunately, the
interfaces in the applications you have written so far look dull. Most
modern applications, and certainly most programs you have used
on the Internet, use visually pleasing graphic objects to interact with
users. These graphical user interface (GUI) objects include the labels,
buttons, and text boxes you control with a mouse when interacting
with Windows-type programs.