Characteristics that distinguish one model of monitor from another include:

Resolution. On-screen image quality is determined by the resolution and color capabilities of both the computer and monitor. Screen images are formed by a grid of thousands of tiny dots, called pixels, and resolution is expressed in terms of the number of pixels appearing on the monitor. For example, resolutions of "800 x 600" or "1,024 x 768" represent the number of columns by the number of rows. In general, the higher the numbers, the sharper the images. Most monitors today are capable of displaying several different resolutions.

However, the number of colors that a computer and monitor can display -- 16 colors, 256 colors, thousands or millions of colors -- also affects the appearance of an image. When displayed on a system that supports 256 colors, image files containing millions of colors may look worse than images with just 256 colors.

The computer's and monitor's resolution and color capabilities must match. Upgrade your computer's video adapter, and a high-resolution monitor will come to life. Conversely, if your computer has a high-res video card, but your monitor's resolution is limited, you'd have to replace the monitor to appreciate the benefits.

You'll often find a jumble of alphabet soup in monitor land. All the terms -- VGA, SVGA, LCD/Flat Panel -- represent steps on the evolutionary scales of monitor development:

Video Graphics Array (VGA) monitors support 640 x 480 resolution in 16 colors.

Super VGA (SVGA) capable of resolutions higher than VGA (640x480). SVGA computer graphics cards have a resolution of 800x600 (480,000 pixels) but may be able to ouput resolutions of up to 1280x1024 and 16 million colors.

LCD Flat Panel Flat panel displays requiring continuous refresh: * Plasma displays* Liquid crystal displays (LCDs)* Digital light processing (DLPs)* Organic light-emitting diode displays (OLEDs)* field emission displays (FEDs)* Liquid crystal on silicon (LCOSs)* Surface-conduction Electron-emitter Displays (SEDs)* Nano-emissive display (NEDs)
The Video Electronics Standards Association (VESA), an international organization composed of PC display and component manufacturers, as well as others in the PC industry, is involved in setting standards for resolution and other monitor functions.

Dot pitch The dot pitch expresses the distance between the pixels on a monitor's screen. The closer the dots are to each other, the brighter the image. A lower dot pitch number means the dots are closer together, so a monitor rated with a 0.28 dot pitch will provide a brighter image than one with a dot pitch of 0.31.

Refresh rate This is the rate at which the screen image is redrawn. Like a motion picture projector, CRTs form images by projecting a series of still frames very rapidly on a screen -- even if the image is motionless. Higher refresh rates result in less flickering on the screen, which is especially important for digital video, animation and video games. A refresh rate of 75 Hz (or 75 frames per second) is commonly found in today's monitors, and is more than enough to support the needs of a home computer user.

Size Monitors commonly come in 15-, 17- and 20-inch sizes, measured diagonally from one corner of the screen to another. One or two inches may not seem like much, but the diagonal measurement translates to a considerable increase in both the width and height (and thus the area) of the screen. Larger monitors serve a couple of advantages: The images displayed are either larger and easier to see, or there's just more on-screen desktop space for more windows and documents. That means less scrolling.

As monitor size increases, so does the price. All but the least expensive systems come with at least a 15-inch monitor today, while 17-inch monitors are becoming more common and less expensive.

Energy efficiency Many monitors now comply with the Environmental Protection Agency's "Energy Star" guidelines, which set a standard of less than 30 watts of electricity usage when the monitor is idle. Monitors achieve this rating, for which other components are also eligible, by shutting off the CRT itself after a set period of inactivity. A trickle of power to the monitor's power supply ensures that the picture will come back up fairly quickly when the user hits a key or moves the mouse.

MPR II Some monitors now come with this rating, a Swedish government standard for devices emitting low levels of radiation. MPR II-certified monitors do not have as much electrostatic potential or emit as great a magnetic field. In Sweden and some other countries, electromagnetic radiation is considered a carcinogen, although no conclusive evidence has emerged to substantiate the fear of the levels of radiation emitted by computers or other consumer electronics.