Window

A window is a key part of the canonical graphical user interface; it divides the display up into regions, and thus allows different application to share the display.

The user usually is given control over how large each window is, where it is displayed on the screen, whether a particular window is 'exposed' or 'hidden', and when windows overlap on the screen, in what order they are shown (much like the ordering of over-lapping sheets of paper on a desk).