Computer monitor

A computer monitor is an output device that shows information in pictures or text. It is a key part of any computer setup, letting you see what your computer is doing. A monitor usually includes a screen, some electronics, a power supply, a case, connectors, and controls you can use.

In the past, most monitors used a technology called a cathode ray tube, or CRT. But by the 2010s, most monitors changed to use LCD screens with LED backlight instead of older CCFL backlit LCDs. This change made monitors thinner and more energy-efficient.

Monitors connect to computers in different ways, such as through DisplayPort, HDMI, USB-C, DVI, or VGA. Some monitors also use special connectors made by certain companies, but this is less common today.

Over time, computer monitors and televisions have become very similar. Both now usually have a display aspect ratio of 16:9 instead of the older 4:3. While monitors usually don’t have built-in speakers, TV tuners, or remote controls, you can still use a monitor like a TV by adding extra equipment such as a DTA box.

History

Early electronic computers used a set of light bulbs on their front panels to show the state of the computer's internal registers. These lights helped engineers watch how the computer was working, and they were called "monitors." At that time, monitors could only show a little information and changed quickly, so they were not used for showing programs. Instead, a line printer was the main way to see program results, while the monitor just helped track the program's operation.

Computer monitors were once called visual display units (VDU), especially in British English, but this term was mostly not used by the 1990s.

Technologies

Further information: Comparison of CRT, LCD, plasma, and OLED displays and History of display technology

Computer monitors have used many different technologies over the years. In the past, most monitors used cathode ray tubes (CRTs), which were large and heavy but could show clear images. Today, most monitors use liquid-crystal display (LCD) technology, which is lighter, smaller, and uses less power. LCD monitors became popular in the 1990s and are now the most common type.

LCD monitors come in many forms, but a special kind called TFT-LCD is now the most widely used. Some newer monitors use organic light-emitting diode (OLED) technology, which combines benefits of both LCD and CRT monitors but can be more expensive.

Measurements of performance

The performance of a monitor depends on several key factors. The size and shape of the screen, known as display geometry, are important. Monitors come in different shapes, called aspect ratios, such as 4:3 or 16:9, which means the width is four units for every three units high, or sixteen units for every nine units high.

Another key feature is display resolution, which tells us how many tiny dots, called pixels, make up the picture on the screen. More pixels mean sharper images. Monitors can also show colors in many different shades, and the quality of these colors is measured in several ways, including how bright the screen is and how well it can show dark and light areas.

Additional features

Most modern monitors have useful extra features. They can save power when not in use, showing a green light when on and an orange light when resting. Many monitors include built-in ports, cameras, microphones, or speakers, making extra devices unnecessary.

Some monitors have special designs like ultrawide or curved screens, and some even let you touch the screen to control things. Professional monitors may include tools for precise color control and other advanced features for specific tasks.

Mounting

Computer monitors come with different ways to be placed or attached, depending on where you want to use them.

A desktop monitor usually has a stand that lifts it up to a comfortable height for viewing. This stand might be special to that monitor or it might fit a standard called VESA mount, which lets you swap the stand for another one if you want.

The VESA mount is a standard way to attach flat screens to stands or walls. Most modern monitors have this, with special holes on the back for attaching them to brackets.

Rack mount monitors fit into special furniture called racks and come in two types: fixed, which stays out and visible, and stowable, which folds down into the rack for storage.

Panel mount monitors are made to fit into thin surfaces, with edges that help them stick in place securely.

Open frame monitors are the basic screens without a full case, meant to be built into other devices, like arcade games.

Security vulnerabilities

Some security agencies have been known to switch monitor cables on certain computers to allow remote viewing of what is shown on the screen.

There is also a method called Van Eck phreaking, where someone can try to see what’s on a screen by detecting signals it gives off. This works best with older screens but can sometimes affect newer ones too, though modern screens are designed to reduce this risk.