As seen earlier, video specification used to be rated in amount of horizontal lines. This is still a current way of expressing the resolution of a video signal. As per the above example, 480i tells us that the signal has 480 picture lines. But because of the way more modern, digital screens work, this specification is somewhat limited in what it can tell us of that particular image or screen. In later years, as video signals and monitors became digital, the resolution of video in the digital era has to be related to digital format. Now, a signal is interpreted in amount of pixels. A pixel is literally short for a "picture element" or the single smallest dot of information, which makes up an entire picture. Picture or screen resolution is now expressed in terms of the amount of detail (or pixels) each image (or screen) has. The amount of pixels is generally expressed as amount of horizontal pixels x the amount of vertical pixels. E.g. 1366 x 768. In the example the screen has 1366 pixels horizontally (over the width) and 768 pixels vertically (over the height). This means that the total amount of pixels the screen or image has are (1366 x 768) = 1049088 pixels.