As far back as the 1850s, people tried to send images over telegraph wires, but the methods were not able to provide quality images and displays. In the 1930s, The Associated Press finally succeeded and began transmitting news pictures, and it had immediate success; people loved illustrations with their news.

Today, monitors make it possible to display pictures with amazing speed and quality; they have increasingly replaced hard copy as the preferred method of accessing text and images; and they have become our doors to the Internet and the digital universe.

SIZE DOES MATTER

One of the first things buyers notice about a monitor is its size. Cathode ray tube (CRT) monitors are the most common and are sold in 14-, 15-, 17-, 19- and 21-inch models. Fifteen-inch monitors are predominant in today's PC systems, with 17 inches being the most common upgrade.

Larger monitors can improve the way things look on your screen and keep graphics moving faster, which are the most common reasons for an upgrade. Smaller screens can be set for higher resolutions, but the result will be images that are smaller and difficult to read or distinguish.

However, larger screens have larger tubes that require more room, creating a problem for users with limited desktop space -- imagine having a 19-inch TV on your desk.

Quality 17-inch monitors cost about $700. Users can get a high-quality 21-inch monitor, ideal for desktop publishing or design, for about $2,000.

When considering a monitor's size, be aware that its size is not the same as its viewable or usable area. Manufacturers provide the viewable screen sizes, in addition to the CRT sizes, of their monitors. Since the picture tube is inside a plastic casing, the viewable screen size is smaller than the CRT or monitor size. For example, a 14-inch monitor can have a viewable area that varies from 13 inches to 13.5 inches, while a 17-inch monitor can range from 15.5 inches to 16 inches of viewable area.

Larger monitors require greater viewing distance. Ideally, users should sit at a distance that allows them to see the entire screen without severe head or eye movement -- 20 inches for a 15-inch monitor and 30 inches for a 17-inch monitor.

THE MONITOR BEHIND THE MASK

A CRT uses masks -- a shadow mask or an aperture grille mask -- to align the tube's electron beam on the color phosphors, which create the screen images.

Shadow mask monitors use dot pitch -- the distance between dots on a monitor -- as their measurements. The smaller the distance between dots the better the image. Dot pitch is measured in millimeters. For example a .28mm dot pitch will produce a sharper image than a .39mm dot pitch. Most monitors come with dot pitches of .25 mm to .28 mm. A shadow mask tube is less expensive to produce and more commonly used in the market. They offer displays with more precision for word processing and spreadsheet applications.

Aperture grille monitors are more expensive and provide better graphics with saturated colors and brightness, which makes them ideal for desktop publishing and design work.

CRAZY FROM THE HEAT

Larger monitors use more power and thus produce more heat and electromagnetic field (EMF) emissions. Power consumption can be as high as 128 watts when a monitor is active. But almost all monitors have a feature that activates a low-power or sleep mode, which can drop power consumption to 30 watts.

Even though the effects of long-term exposure to a monitor's EMF emissions has not proved harmful, there is concern among many users. However, the MPR II standard for EMF emissions provides the most stringent guidelines for maximum radiation levels.

IN NEED OF REFRESHMENT

Since many of us stare at monitors for up to 12 hours