A monitor display is an essential part of your computer system. Though it's considered a peripheral, your computer can't really be used unless you have a monitor. That's because it displays the results of whatever your computer is processing. In addition, it's used for viewing the Internet, for playing video games, sorting through your digital pictures and assorted graphic applications.

  1. CRT - CRT means Cathode Ray Tube. This monitor uses similar technology found on most TV sets that have been around for the last 50 years. As viewing screens become larger, the depth and weight of the overall monitor's cabinet grew as well. This means that a monitor with a 17-inch (diagonal) screen would be about 19 inches deep and weigh about 50 pounds. One with a 20-inch screen might be about 24 inches deep and weigh around 90 pounds. Many of these monitors sell at below $500. By the end of 2006, it is likely that very few CRT monitors will be marketed to the public.

  2. LCD - LCD means Liquid Crystal Display. Flat-panel monitors have screen sizes from 15 inches to over 22 inches. They all measure about 7 inches deep (with stand) and 2 inches deep (without stand). They weigh from about 2 pounds to about 20 pounds on average. Many may be mounted on a wall. LCD monitors sell at around $250 and higher. Most LCD and Plasma televisions (which can have screens as large as 80 inches) may also be used as computer monitors but, because they aren't primarily used as monitors, they're not covered in this section.

LCD monitors offer larger screen sizes while taking up less space on our desks and tabletops than the CRT models. The flat-panel LCD would seem the most ideal choice but, if you're using it for playing action games, there's a disadvantage. Its response time is slower than tube models. This means that rapidly moving images might have a shadowing effect. New LCD monitors are delivering much faster screen response times for optimal video and gaming action.

A monitor's display is measured diagonally in inches. Most CRT tube monitors have a border, and once they are turned on, the real viewing size is smaller than what was measured diagonally. This is referred to as the Viewable Image Size (VIS). VIS is usually an inch or so less than the actual diagonal size measure. This means that a CRT monitor with a 17-inch screen may have a VIS of about 16 inches. LCD monitors, on the other hand, have no borders so on a 17-inch LCD screen the VIS is 17 inches.

Most stand-alone monitors range in size from 15 inches to about 21 inches. How much viewing space you need is completely up to you. A larger screen would be easier to read, play games on, and keep more windows open.

Some LCD monitors offer different size orientations. This means the ability to pivot the display from the landscape to portrait. Landscape is the traditional screen appearance. Portrait is like putting it on its side so it appears more vertical. This position is preferred among those that do lots of word-processing and desktop publishing because it shows a page completely at once.

The resolution of any monitor refers to how many pixels (picture elements) and horizontal lines are on one screen. The resolution figure is always going to look something like 1280 X 1024 (read 1280-by-1024). The first number refers to the number of pixels in one horizontal line, and the second number refers to how many pixels per line vertically. In most cases, a monitor's control panel allows resolution adjustments to meet specific needs.

Essentially, higher numbers mean higher resolution. Most monitors are geared for 1024x768. Most Internet applications suggest viewing at either 800x600 or 1024x768. When running a detailed graphics program (i.e. Adobe Photoshop) you may want to go to 1600x1200 or higher. In cases where very high resolutions are necessary, you need:

1. A monitor capable of presenting very high resolutions;
2. A graphic processor in your computer, with enough video memory, to support such presentations;
3. Generally, a monitor with a large size screen (19 Inches or more).

If you examine a television or computer monitor screen closely, you'll see that it's made up of tiny little dots aligned side by side. Each dot comes in three colors. The Dot Pitch rating of a monitor tells you just how sharp the displayed image will be. Dot pitch is measured in millimeters (mm), and a smaller number means smaller size and, subsequently, a sharper image. Dot Pitch size is also proportional to the size of a monitor's screen. While 0.25mm might be great on a 15" monitor, a 20" monitor with 0.30mm dot pitch would offer comparable image quality.

CRT Monitors have really no issues when it comes to contrast; displaying deep blacks and pure whites is really easy. Among many LCD screens, when contrast ratios fall below 200:1, black tones appear more gray than black. That's why LCD screens are rated by contrast ratios. As the ratio increases (let's say 450:1) black tones appear deeper and more precise.

A monitor displays black and white tones mixed with millions of colors in between. Contrast Ratio is associated with how many black tones. A 300:1 contrast ratio means there are 300 depths of black to one white.

300:1 is suitable for business applications but, when it comes to dealing with images for more critical needs, you want to search for ratios of 500:1 or more.

Higher contrast ratios allow for better video imaging.

A CRT display works somewhat similar to a light bulb. Phosphors are ignited around the pixels to convey a bright image. In LCD screens, a built-in light illuminates the visual field.

Ratings for brightness are usually indicated as a number followed by CD/M2. This represents Candela per Meter Squared. A Candela is a degree of luminous intensity in a given direction, also referred as 'candlepower'. Another rating is 'Nits'. A nit is a unit of measurement of luminance, or the intensity of visible light, where one nit is equal to one candela per square meter. Nits are used to describe the brightness of computer displays, such as LCD and CRT monitors. Basically, an increase in the number of Nits or Candelas results in the brighter output of the screen.

At about 400 CD/M2, an LCD monitor can appear brighter than a comparably sized CRT. Typically, you want to aim for a brightness of 400 CD/M2 for a computer monitor used for video and gaming.

Ever wonder how the image you see on your television or computer screen gets there? What really happens is one dot is scanned so quickly across your screen it forms a complete picture. The interval between when the dot begins its journey across your screen, lighting up all the dots along the way, to when it finishes, is one cycle.

The refresh rate means the number of times an image is displayed in one second. It is expressed in Hertz (Hz), so a monitor with a refresh rate of 75 Hz displays an image 75 times a second. Less commonly referred as the "horizontal refresh rate", it's the number of times per second that the electron beam travels along a line and returns at the start of the next. The number of horizontal lines varies with the desired resolution. If you choose 1024x768 as a resolution, then there are 768 horizontal lines. The higher number of "Hertz" means the speed of the refresh rate and the optimal speed is the rate at which your display doesn't seem to flicker. Most screens today have refresh rates that are 70Hz or quicker.

When dealing with large screens at high resolutions, achieving an optimal refresh rate may require a higher performance video processor with more video memory installed in your computer.

Response time sounds something like Refresh Rate (see above) but corresponds to an LCD screen. The nature of the LCD is a slower decay of imaging on the screen surface. As such, visual scanning can appear jagged. To obtain smoother fluidity of movement, an electronic circuit tweaks the display to respond faster to signal changes. The rating is measured in Milliseconds (each being one 1/1000th of a second). The lower number of milliseconds means a faster screen response time.

LCD display manufacturers have been steadily improving response times as the demand for fast moving full motion video has increased. A good response time starts at around 25-30 milliseconds (ms). Newer model LCD monitors have response times that are within the 8 to 16ms ranges. This is really fast. 1000 milliseconds are equal to 1 second. 25ms is less than a blink of your eye.

Response Time refers to the screen's signal reaction speed - basically the time required for the screen to turn from completely white to completely black and vice versa. If each cycle takes 12ms, two complete cycles take about 25ms.

So when a display is rated at a certain response time, does it rate one cycle or two cycles? When it comes to rapidly moving game graphics, however, there are critical elements that extend beyond black and white. What about colors? Do Response Times account for color changes? In many cases, it doesn't. While response time is a significant indicator of the ability to realistically display motion on a screen, it isn't the only ingredient in the recipe. Sometimes it's advisable to see how the display performs when running your software.

If you want to use your LCD monitor for action games or for video output, it's advisable to aim for 10 millisecond response or lower.

You don't really find many Plasma flat-panel computer monitors. Virtually all flat-panel computer displays are LCD but many Plasma TV monitors have ports that are compatible for computer connectivity.

Though the average person may not need a 50-inch size screen, there are business and academic applications where a large screen is very helpful when lecturing to a group of people. In most instances, however, multimedia projectors are more economical, more portable, and most commonly used.

A Multimedia Projector is a monitor that projects an image onto a wall or, preferably, a projection screen (not unlike one you would see in a movie theater). The "multimedia" concept relates to the various type of connectivity ports that may be found on any model. It not only projects computer images but can also project TV and video images, depending what's connected to it.

Most models weigh less than 10 pounds so they are very portable and can be easily transported from one place to another.

Most use reflected LCD panel technology that's illuminated by a bright light bulb. Image brightness can be very high, bright enough to be viewed in a moderately dark room - total darkness isn't required. Resolutions generally fall into the 800x600 SVGA or 1024x768 XGA image ranges. At 1024x768, some models may be used to project HDTV - with an optional HD Tuner hookup. Some models may be capable of reaching even higher resolutions.

Projected image sizes can go from 36 inches to over 120 inches (measured diagonally).

Since these projectors present very large images, they may also be used by the visually handicapped.

If you use your computer for digital photo, video, graphics, animation, and 3D gaming, you may wish to use large screen monitors with very high-resolution capabilities. Some computers may not have the video/image processing power required to get optimal performance.

Installed inside your computer in an available PCI or AGP port, these card provide additional memory plus new 3D graphic and game technologies. Some boards also offer capabilities for capturing images from external devices like digital cameras, camcorders, TVs, and VCRs. Some boards allow presentation onto standard TV screens.

Most monitors (currently sold) are compatible for use with most PC systems and Macintosh computers (manufactured from 2001 to current).

Different cables are available for connecting monitors to PC and Macintosh computers. Standard VGA and RGB computer-to-monitor connections usually come with the purchase of any monitor.