The display resolution of a digital television or computer display is the number of pixels (or maximal image resolution) that can be displayed on the screen, usually given as a product of the number of columns (horizontal, "X") is always stated first and the number or rows (vertical, "Y") make up the aspect ratio.

For analog TV sets, the horizontal resolution is related to the bandwidth of the luminance signal, and is stated in "lines", as the largest number of alternating vertical black and white stripes that can be displayed across the width of the picture without them merging together. Sometimes, the lines are counted across a width equal to the height of the picture, rather than across the full width of the picture. This gives rise to two different measures of horizontal resolution, which can lead to confusion. The vertical resolution, as with digital displays, is the number of horizontal lines in the picture.

Currently, common computer display resolutions are 640×480 (VGA, Video Graphics Array), 800×600 (SVGA, Super VGA), and 1024×768 (XGA/XVGA, eXtended). Some computer users, especially CAD users and video game players, run their computers at 1600×1200 resolution (UXGA, Ultra-eXtended) or higher if they have the necessary equipment. When a computer display resolution is set that is too high for the display, some systems make the virtual screen scrollable over the physical screen. With digital television and HDTV, vertical resolutions of 720 or 1080 scan lines are typical.

The 640×480 resolution, introduced with the IBM PS/2 VGA and MCGA (multi-color) on-board graphics chips, was the standard resolution from 1990 to around 1997, partly due to its 4:3 ratio. 800×600 has been the standard resolution from 1998 to the present, but 1024×768 is fast becoming the new standard resolution, especially since it also satisfies the 4:3 ratio. Many web sites and multimedia products are designed for 1024×768 resolution. Most of today's computer games released during the "128-bit video game era", such as SimCity 4, do not support 640×480 at all. Windows XP is designed to run at 800×600 minimum (although it is possible to run legacy applications in 640x480 compatibility mode).

As of 2005, approximately 30% of computers with web access use a computer with 800x600 resolution; less than 2% of web site views use a computer with only 640x480 resolution.

With 15" and 17" (381 mm and 432 mm) monitors, 1024×768 resolution is the standard, whereas with 19" (483 mm) monitors, 1280×1024 is the recommended standard. Good 21" (533 mm) monitors are usually capable of 1600×1200 resolution. There are also 24" (610 mm) widescreen monitors on the market, and those will often be able to display 1900+ pixels horizontally.

See also: computer display standards