What is the refresh rate?
Updated
Refresh rate refers to the capability of a monitor to show multiple frames per second. It is typically measured in Hz ("Hertz"), where a monitor with a 60Hz refresh rate refreshes the displayed image 60 times per second.
If the refresh rate of your monitor is less than the frame rate sustained by your GPU, you may experience image problems like tearing. While there are usually options available to limit the frame rate produced by your GPU, in doing so, you lose out on the previously mentioned benefits of a higher frame rate.
As such, many modern monitors now offer higher frame rates above the classic 60Hz. Some commonly supported higher refresh rates are 75Hz, 100Hz, 120Hz, 144Hz, 165Hz, 240Hz, and even as high as 360Hz. Moving from a 60Hz display to a 144Hz normally offers a significant improvement in viewing experience, assuming your GPU can maintain a matching frame rate.