The refresh rate of a monitor
is the maximum number of times the image on screen can be "drawn" per second, measured in hertz (Hz).
To understand refresh rate, you need to realize that the image on a monitor screen (at least the CRT kind) is not a constant image. It is "redrawn" over and over so quickly (anywhere from 60 to 100 times or more per second) that the human eye perceives it as a static image, or a smooth video, etc.
On a Windows XP PC for example, you can adjust the refresh rate setting to reduce "flicker" and other unstable display issues.
Also Known As: scan rate
Examples: "After hooking up my new monitor, I noticed that the image was flickering very quickly which was giving me a headache. I finally realized that the refresh rate was set too low at 55 Hertz so I raised it to 85 Hertz, the maximum rate my particular monitor supported, which fixed my problem immediately."