Monitor is another word for the computer screen. But "monitor" encompasses the whole piece of equipment, rather than just the screen part that you look at. You also might hear a monitor called a display, as in "Oooh, I got a new two-page display," or VDT(video display terminal), as in newspaper journalism, or CRT (cathode ray tube), which is the technical term for a picture tube. However, flat panel screens like LCDS are not referred to as monitors, even if they're housed externally from a computer.
Some monitors are built right into the computers, like in the small Macintoshes. When you purchase a larger Macintosh or most other kinds of computers, you must buy the monitor separate from the computer itself (that's why they're called "modular"). Monitor size is measured like a television, from one corner to the diagonally opposite corner.
Some monitors are monochrome, meaning they can show only one color on a background, like black on white (Macs), green on black, or amber on black (pcs). Grayscale monitors can display different shades of gray, rather than imitating the different shades with combinations of black and white dots. And there are many different color monitors. A color monitor can display any of several levels of resolution and can display varying numbers of colors, determined by several factors, such as amount of memory in the computer or the type of card that is controlling the monitor. See the section in Appendix A on how to read a computer monitor advertisement.