CRT monitors use an electron beam that hits phosphor dots inside of a vacuum tube. While it is possible for a CRT monitor to have a digital connection, virtually all CRT monitors connect to the video card using a DB-15 (also called a D-sub) connector. Be aware that the display qualities of your monitor depend on the capabilities of both the monitor and the video card. When choosing a CRT monitor, keep in mind the following considerations.
Consideration
Description
Screen size
Screen size is often expressed in two different measures:
The physical screen size (also called the actual size). This is the diagonal measure of the display tube.
The effective viewing size identifies the largest image size that can be displayed. Because of how the CRT monitor works, portions of the display tube cannot be used for displaying the image.
Graphic artists, multimedia designers, and programmers often need much larger displays.
Resolution
The resolution is the number of pixels available on a display screen. Specifically, the resolution is described by the amount of pixels horizontally across the display by the amount of pixels vertically down the display. Monitors that support a higher resolution can display higher-quality graphics or have a larger screen area.
Display type
There are two methods of controlling the illumination of the phosphor:
A shadow mask consists of a metal screen full of holes that are aligned with each dot. The screen shields the electron beam from illuminating between dots and leaves an outline around each pixel.
An aperture grill consists of a screen of ultra-thin vertical and horizontal wires. This configuration allows more electrons through resulting in a richer color display. On an aperture grill monitor you might be able to see two horizontal lines running across the display. These lines are the wires that are used to dynamically change the grill opening.
Dot pitch
The dot pitch is the distance between pixels. This is measured in millimeters. The standard dot pitch in color monitors in about .15 mm to .30 mm. The smaller the dot pitch, the more room there is for higher resolutions and the sharper a picture may be.
Refresh rate
The refresh rate is the amount of time required for the CRT's electron beam to paint the screen from top to bottom. Increasing the refresh rate reduces screen flicker. Refresh rates are measured in Hz.
Interlacing
Interlacing is drawing the screen in two passes; odd lines on the first and then the even lines on the second pass. Non-interlaced monitors produce the least amount of flicker.
Additional features
Additional monitor features include:
Green monitors that are Energy Star or Green Star compliant. These monitors use less than 30 watts and reduce power consumption by 99% when in sleep or suspended mode.
Flat displays (tube monitors with a flatter glass tube). A flatter display results in an image with less distortion around the edges.
Built in speakers or USB hub.
CRT monitors have a 4:3 aspect ratio, which matches the display ratio of a television set.
The magnetic field used for drawing the image on the screen can cause a buildup of magnetism on internal monitor components. This magnetic field can cause color distortions, especially around the edges. To correct this problem, use the degauss feature of the monitor. Degaussing creates an oscillating magnetic field for a short period of time. Most monitors perform degaussing automatically when they are turned on, but you can also manually initiate degaussing using the monitor's front panel controls.

LCDs are flat panels that use a liquid crystal material and transistors to display images. TFT (thin film transistor) and active matrix are additional terms that are often used to describe LCD monitors. Currently, all LDC displays are TFT and active matrix displays. The following table describes various characteristics of LCD monitors.
Factor
Description
Display characteristics
As you compare LCD monitors,