LCDs, or liquid-crystal displays (also called flat panels or flat screens), are thin sandwiches of glass containing a liquid-crystal material. When exposed to electric current, the molecules of liquid-crystal material change their alignment to either transmit or block light, which ultimately creates an image. Each pixel is composed (in most cases) of red, green, and blue subpixels. LCD monitors cost more than same-size, old-school CRTs, but they offer a few significant advantages. Here's how LCDs stack up, for better or worse.

Pros	Cons
Thin and stylish	Relatively expensive
Energy efficient	Fragile
Relatively lightweight, especially in larger sizes	Limited viewing angle
Crisp image	Color rendition may be limited or inconsistent
More display area (a 15-inch LCD is equivalent to a 17-inch CRT)	Moving images may smear
No refresh-rate flicker	May flicker from inability to synchronize with signal correctly
Little or no low-frequency electromagnetic emissions compared with a CRT	Image quality is greatly reduced when running in nonnative resolution, because the image must be scaled to match the pattern of physical pixels
Perfect screen geometry
No convergence problems

The original CRT (cathode ray tube) technology was invented more than 100 years ago and has been greatly refined since. Inside a color CRT, three electron guns shoot streams of electrons at the screen. A mask blocks the electrons so that the beam from one gun hits only red phosphor dots on the screen, just as the beams from the other guns only hit green or blue phosphors. By controlling the position of the beams and how fast they turn on and off, a CRT can create pixels of varying sizes, so it can produce different-resolution images with little loss of image quality. Although they're big and boxy, CRTs are inexpensive--and indispensable for some computing tasks such as video-editing and gaming. Here's a look at the good and the bad in CRTs.

Pros	Cons
Relatively inexpensive	Large and bulky
Rugged	Energy inefficient
Unlimited viewing angle	Relatively heavy, especially in larger sizes
Generally good color rendition	Pixels are not clearly defined at any resolution
Moving images do not smear	Less display area (a 15-inch LCD is equivalent to a 17-inch CRT)
No flicker from problems with synchronizing with a signal	Refresh-rate flicker is below 75Hz; flicker is more severe with larger monitors
Can display different-resolution images with relatively little loss of quality	More low-frequency electromagnetic emissions than LCDs
	Nearly impossible to get perfect screen geometry, especially with flat-faced CRT designs
	Almost impossible to get perfect convergence of red, green, and blue beams on all parts of the screen