A windows decoration typically consists of a title bar, usually along the top of each window and a minimal border around the other three sides. On Microsoft Windows this is called "nonclient area".
In the predominant layout for modern window decorations, the top bar contains the title of that window and buttons which perform windowing-related actions such as
The border exists primarily to allow the user to resize the window.
Window decorations are considered important for the design of the look and feel of a desktop environment and some systems allow for customization of the colors, styles and animation effects used.