A window is conceptually the frame in which an application is rendered. It is generally created and managed through OS API calls. Some game engines will abstract these calls and integrate the functionalities into their own API. This tag should be used on questions interacting with OS's windows. It is _not_ about Microsoft's Windows operating system.

A window is conceptually the frame in which an application is rendered.

The concept of windows is generally found of desktop computers' operating systems such as Windows, Mac OSX and Linux. Since these OSs manage larger screen, the user can have multiple programs visible at one time, so the OS lets the user arrange these window how they like.

On mobile platforms, the concept of window is much less present as the applications generally occupy the whole screen.

Windows are generally created and managed through OS API calls. Some game engines will abstract these calls and integrate the functionalities into their own API to simplify the developers life, and to keep a nice homogeneity with the rest of the engine's features.