viewable area 
Monitor sizes aren't as straightforward as they seem. A 17-inch CRT monitor measures 17 inches diagonally across the glass face of its picture tube, including the part covered by the bezel. However, the viewable area of the monitor--the diagonal measurement of the largest possible picture the screen can display--is never as large as the actual tube size. Thus a 14-inch monitor typically has a viewable area of 13.1 inches, a 15-inch monitor offers about 14.3 inches, and so forth. Because LCD monitors and panels used in notebooks can display images out to their very edges, their physical and viewable diagonal measurements are the same. Thus a 17-inch LCD monitor offers very nearly the same viewable area as a 19-inch CRT monitor.