Term: Focus

Focus is the concept that, in a multi-window operating system (such as Microsoft Windows or Mac OS), user input can be directed to only one application window at a time.

An application (such as a keyboard or mouse) is said to have focus when it receives user input. This application is usually (although not always) in the foreground; its window is displayed on top of or in front of any other application windows.

The concept can apply within an application as well. A dialog box – perhaps a “File, Open” file selection box – may take the focus away from the main application window until the dialog is dismissed.

An application that takes focus from another application unexpectedly, or without interaction from the user, is sometimes said to “steal focus.” An example might be when a user is typing in one program, and suddenly sees that some or all of the input is being entered into some other application that at some point “stole focus”.