Windows 95 introduced a redesigned shell based around a desktop metaphor; the desktop was re-purposed to hold shortcuts to applications, files, and folders - unlike Windows 3.1 where it was used to display running applications. Running applications were now displayed as buttons on a taskbar across the bottom of the screen, which also contains a notification area used to display icons for background applications, a volume control, and the current time. The Start menu, invoked by clicking the "Start" button also contained on the taskbar, was introduced as an additional means of launching applications or opening documents. While maintaining the program groups used by its predecessor, Program Manager, it now displayed applications within cascading sub-menus. The previous File Manager program was also replaced by Windows Explorer.