The refresh rate is the number of times a display refreshes in a second to show a new image. The unit of frequency is Hz (hertz). Therefore, 144Hz means the display refreshes 144 times per second to show a new image, 120Hz means the display refreshes 120 times per second to show a new image, and so on.

A 144Hz monitor can show 144 unique frames per second with 6.94ms between each frame, whereas a 240Hz monitor shows 240 frames with 4.17ms between each frame. This means that a 240Hz monitor can show a new image 2.77ms faster than a 144Hz display.