Computers, Laptops & Tablets Accessories & Hardware What Is a Monitor? Definition, facts, and troubleshooting guide By Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated November 15, 2019 Accessories & Hardware Monitors Keyboards & Mice Cards HDD & SSD Printers & Scanners Raspberry Pi Tweet Share Email A monitor is a piece of computer hardware that displays the video and graphics information generated by a connected computer through the computer's video card. Monitors are similar to TVs but usually display information at a much higher resolution. Also unlike televisions, monitors typically sit atop a desk rather than being mounted on a wall. A monitor is sometimes referred to as a screen, display, video display, video display terminal, video display unit, or video screen. The 8 Best Computer Monitors of 2020 General Monitor Description On a desktop computer, the monitor connects via a cable to a port on the computer's video card or motherboard. Even though the monitor sits outside the main computer housing, it's an essential part of the system. It's important to differentiate between the monitor and the actual computer, especially on a desktop system. Shutting off a monitor connected to the computer isn't the same as powering down the actual computer, whose components (such as the hard drive and video card) are housed within the computer case. Monitors are built-in as part of the computer in laptops, tablets, netbooks, and all-in-one desktop machines. However, you can buy one separately if you want to upgrade from your current monitor or configure a multi-monitor setup. Monitors come in two major types, LCD and CRT. CRT monitors, which are deep in size, look like old-fashioned TVs. LCD monitors are much thinner, use less energy, and provide better graphics quality. OLED is another type of monitor that's an improvement on LCD, providing even better color and viewing angles but also requiring more power. LCD monitors have obsoleted CRT monitors due to the higher quality, smaller footprint on a desk, and decreasing price of LCDs. However, OLED monitors are still more expensive and therefore not as widely used in the home. Most monitors range in size from 17 inches to 24 inches, but others are 32 inches or more, some even much wider like the gaming monitor shown above. The size of a monitor is measured from one corner of the screen to the other, not including the outer casing. Most monitors are considered output devices since they usually only serve the purpose of outputting information to the screen but some of them are touch screens as well. This type of monitor is considered an input/output device, or an I/O device. Some monitors have integrated accessories like a microphone, speakers, a camera, or a USB hub. Important Monitor Facts The most popular brands of computer monitors include Acer, Hanns-G, Dell, LG Electronics, Sceptre, Samsung, HP, and AOC. You can purchase monitors from these manufacturers directly or through retailers like Amazon and Newegg. A monitor usually connects to an HDMI, DVI, or VGA port. Other connectors include USB, DisplayPort, and Thunderbolt. Before investing in a new monitor to use with your computer, make sure both devices support the same type of connection. For example, don't buy a monitor that has an HDMI port when your computer is only capable of accepting a VGA connection. Although most video cards and monitors have multiple ports to work with various kinds of devices, it's still important to check their compatibility. If you do need to connect an older cable to a newer port (such as HDMI to VGA) there are adapters for this purpose. Troubleshooting Monitor Issues The performance of a monitor is usually determined by a number of factors and not just one feature like its overall screen size, for example. Some of them include the aspect ratio (horizontal length against the vertical length), power consumption, refresh rate, contrast ratio (concentration of the brightest colors vs the darkest colors), response time (how long it takes a pixel to go from active, to inactive, to active again), display resolution, and others. You may be able to address many monitor problems yourself, though, for safety reasons, it's best not to open the casing. If you can't solve the issue with the suggestions listed here, take your monitor to a professional. Setup. Monitors are usually instantly available through plug and play. If the video on the screen doesn't appear as you think it should, consider updating the video card driver. See How to Update Drivers in Windows if you need help. Cleaning. Newer LCD monitors should be cleaned with care and not like you would a piece of glass or older CRT monitor. If you need help, see How to Clean a Flat Screen TV or Computer Monitor. No image. Are you dealing with a monitor that isn't showing anything on the screen? Read our guide on How to Test a Computer Monitor That Isn't Working for steps that involve checking the monitor for loose connections, making sure the brightness is properly set, and more. Inaccurate display. Read How to Fix Discoloration and Distortion on a Computer Screen if your monitor doesn't seem to be displaying things like it should, like if the colors seem off, the text is blurry, etc. Color problems on an older monitor. If you have an older CRT monitor that has a problem displaying colors like if you see an array of colors around the edges of the screen, you need to degauss it to reduce the magnetic inference that's causing it. See How to Degauss a Computer Monitor if you need help. Screen flickering. Screen flickering on a CRT monitor can be solved by changing the monitor's refresh rate, something you can do from the Windows Control Panel.