The most stared-at object in the world -- at least according to a recent survey among software professionals -- is the computer monitor! It doesn't sound that far-fetched, considering most of us spend a few hours of every day in front of one, be it at the office or while studying at home.

For now, let's talk about the categories of monitors available, and parameters you need to keep in mind before picking one. We begin with the different hardware technologies available.

Cathode Ray Tube

Commonly known as CRT monitors, these are the same as the picture tube inside your televsion. They work by firing beams of electrons at phosphor dots on the inside of a glass tube. The phosphors are chemicals that emit red, green or blue light when hit by electrons. These monitors are capable of multiple resolutions, give the best look to full-motion video and provide better control over colour calibration for graphic artists.

On the down side, they hog a lot of room and weigh more than several sacks of potatoes. You can get more compact CRTs -- called short-depth or short-neck monitors � that are a couple of inches shallower than regular CRTs. Unless space is a primary consideration, most people buy a CRT display because they offer good performance at an affordable price. These days, Flat Screen CRT monitors are also available. Flat CRTs are designed to reduce the glare and distortion created by conventional CRT monitors. The flat tube increases image clarity, while reducing glare from light sources within the room.

Advantages
� The technology behind CRT monitors is quite dependable and has been in use for several years now.
� CRT monitors are quite cheap compared to other categories of monitors.

Drawbacks
� The size and weight of CRT monitors is the only drawback for this technology.

Liquid Crystal Display

Commonly known as LCD monitors, these are commonly used in laptops and fast becoming popular as desktop monitors. Their major selling points are a slim profile and light weight. A CRT can be deeper than it is wide, whereas a LCD with a base is only about a hand span deep. LCDs weigh less than half the average CRT. They require half the power of CRTs and emit much less electromagnetic radiation, which can interfere with other electronic devices.

In the screen of an LCD monitor, each pixel is produced by a tiny cell, which contains a thin layer of liquid crystals. These rod-shaped molecules bend light in response to an electric current. LCDs tend to be clearer than CRTs, which can suffer from convergence or focus difficulties. Their improved clarity means that even small LCDs can display higher resolutions than a CRT of the same size. They also make small text easier to read. Unlike CRTs, LCD monitors have only one optimal resolution. At lower resolutions, the screen is redrawn as a smaller area or all pixels in the image are blown up to fill the screen. A variant of LCDs called TFT monitors (Thin-Film Transistors) improves image quality.

Advantages
� LCD monitors are very compact, occupy less space and are lightweight.

Drawbacks
� The viewing angle of a LCD is usually less than that of most other display technologies, reducing the number of people who can conveniently view the same image.
� LCD displays generally have a lower contrast ratio than that on a plasma display or CRT.
� While CRTs are capable of displaying multiple video resolutions, LCD displays usually produce only crisp images in their 'native resolution' or even fractions of it i.e. changing resolutions on LCD screens is not recommended.

Plasma Screens

Plasma Display Panels (PDP) are emissive flat panel displays where light is created by phosphors excited by a plasma discharge between two flat panels of glass. Plasma displays are bright (1000 lx (Lux) or higher for the module), have a wide colour gamut, and can be produced in fairly large sizes -- up to 262 centimetres (103 inches) diagonally. The display panel is only about 6 centimetres (2 1/2 inches) thick, while the total thickness, including electronics, is less than 10 centimetres. The image is very bright and has a wide viewing angle.

Advantages
� Slim design.
� Sizes larger than LCD screens
� More viewing angles than LCD screens.

Drawbacks
� Plasma displays are very fragile.

Besides Plasma, LCD and CRT displays, research is also being done on Surface-conduction Electron-emitter Display (SED) and Organic Light-Emitting Diode (OLED) display. Coming to technical specifications, monitors are categorized on basis of size, aspect ratio, dot pitch, resolution and refresh rate.

Size

The size of a monitor refers to its width. The width is not a horizontal measure of the screen. The size of the monitor is measured as the diagonal length of the screen of the monitor. Hence, the 17" regular monitor will be smaller in size when compared to a 17" Flat Screen monitor.

Resolution

Determined on the amount of individual pixels on a screen, measured horizontally by vertically. Resolution of a screen remains the same no matter the screen size, so a 17" screen with a 1024 x 768 resolution will show a clearer picture than a 23" screen with a 1024 x 768 resolution, due to a lower dot pitch.

Refresh Rate

Refresh rate is how many times per second a screen can redraw itself, or 'refresh'. To avoid flickering, a screen must have a refresh rate of at least 72 Hz.

Dot Pitch

A computer monitor displays an image made up of millions of pixels, or 'dots'. Dot pitch refers to the distance between each pixel. The lower the dot pitch, the less distance between pixels, and the sharper the image.

Aspect ratio

Aspect ratio is the width of your computer monitor versus the height of your monitor. The traditional monitor has an aspect ratio of 4:3, and some wide screen monitors have an aspect ratio of 16:9 (sometimes 15:9 or 16:10).

All prices sourced from Nehru Place Hardware Market, New Delhi.