CRT Monitors:
CRT is the acronynm for cathode-ray tubes. This technology has been around for about 100 believe it or not and is found in most TV's and computer monitors. Cathode ray tubes work by moving electrons in a beam back and forth across the back of the screen. As the beam makes a pass across the screen, it lights up phosphor dots on the inside of the glass tube, which then illuminates the active portion of the screen. By drawing many of these types of lines from the top down to the bottom of the screen it creates and entire screen of images.

LCD/Flat (screen) panel Monitors:
LCD is the acronymn for liquid crystal display. This is the same technology used in digital watches (usually black numbers on a grey background). LCD's is a liquid crystal solution between two sheets of polarizing material. An electric current is then passed through the liquid which then causes them to align so that light is unable to pass through. The crystal in a sense is acting like a curtain, so it can either allow the light to pass through or not. This is how the black and white (or grey as mentioned before) works. Color LCD's work similarly but a little different. There are two technological methods for producing color. One is called Passive Matrix which is the less expensive of the two. Active matrix or the acronym TFT (thin film transistor) which will produce colors and images as sharp as a CRT but are more expensive.

CRT vs. LCD - Pros and Cons

Resolution & Viewing Quality
CRT's can provide you with a wide range of viewing resolutions over 1600 X 1200 in many cases. An LCD has the ability to do the same, however they can be limited by what is known as their native resolution. What this means is that the resolution is fixed when manufactured and designed for that size monitor. You can change the resolution however you will probably notice a drop in quality and or performance.
Both can display excellent color ranges, however CRT's can provide a greater color range vs an LCD. However when you adjust the CRT to display the maximum color range the picture quality can be blemished by soft edges.
CRT's can be viewed by any angle, where as the LCD is limited depending on your angle or distance.

Refresh Rate
LCD's have a faster refresh rate which eliminate the annoying flicker that can be noticed on a CRT due to it's physical componants.

Physical Size
The biggest component is the physical size of the monitors. As most people know, the CRT is a large componant and can be bulky or heavy. For example a 17" CRT can weigh on average 40 lbs where the comperable LCD will weigh 15lbs. Also, if you don't have a lot of room, you will want to seriously look at a flat screen monitor.

Price
The upfront cost of an LCD screen is more expensive then a CRT. However they are known to last longer and use less electricity so over time the cost will even out.