A “control” is a predefined child window that carries out a specific kind of input or output. For example, to get a filename from the user, you can create and display an edit control to let the user type the name. An “edit control” is a predefined child window that receives and displays keyboard input.
A control, like any other window, belongs to a window class. The window class defines the control's window function and the default attributes of the control. The window function is important because it determines what the control will look like and how it will respond to user input. Control window functions are predefined in Windows, so no extra coding is required in your application when you use a control.