In computer terms, this means the number of pixels shown on the screen expressed as the number of pixels on the X (horizontal axis) and on the Y (vertical axis). How sharp your display is is dependent on the resolution, and high amount of pixels in a small monitor will have very sharp display and the other way around. Over the years, the typical screen resolution with PC users has been either 1024 times 768 (1024x768 -- first figure means the number of pixels on single horizontal line and the second figure means the max number of horizontal lines on screen) or 1280x1024. However, now with the growing of popularity of widescreen and HD, the most popular resolutions are becoming 1920x1080, 1440x996, 1280x800 and 1280x720.
Some popular resolutions for media