A refresh rate is the number of times a new image is shown on a screen (such as a television or computer monitor) per second. It is measured in hertz (Hz), which is a measurement of frequency. This means that a screen with a refresh rate of 60 Hz will show 60 images per second. The refresh rate is related to another measurement, the frame rate or frames per second (fps). In relation to a screen, the frame rate is how many images a device (such as a computer) is sending to the screen per second to be shown on the screen.
If a device is running at 30 frames per second, and the screen has a refresh rate of 60 Hz, then 30 images per second will be shown to the viewer. Even though the screen can display more images per second, it is only getting 30 images per second from the device. However, the device runs at 120 frames per second, then only 60 images per second will be shown on the screen. This is because the screen can not display more than 60 images per second (its refresh rate).
As the refresh rate of a screen increases, the amount of images shown also increases. This can make the picture shown on the screen clearer, avoiding motion blur. (Motion blur is when something moves very fast, and it looks blurry. If a screen can not show images fast enough to keep up with an object, motion blur might happen.) Many televisions and computer monitors run at 60 Hz. This is a very common refresh rate. Because 60 frames per second is a common frame rate, 60 Hz monitors can show most things very clearly. However, some people want to have a higher refresh rate, because they use things like video games or very high quality videos, which can have much higher frame rates. Many screens have 120 Hz, 144 Hz, or 240 Hz refresh rates for this reason.