The descriptive text that appears at the top of a window, in white text on a blue background. For example, in Windows 95, double-click on the My Computer icon and you'll see a small window pop up. The top of the window has the caption 'My Computer' in white characters on a blue background. If you click anywhere outside this window, the blue background to the caption turns grey, to show that the window is no longer active. (See also active window.)