What does 30hz, 60hz and 120hz mean?

[Legolas8181]

I often see minitors that are either 60hz or 120hz but what does that mean?

 

[sweenytodd]

It means standard refresh rate for high-definition displays. The refresh rate indicates the number of times a display is repainted per second, in hertz; a 60hz refresh rate indicates that a display is repainted 60 times per second; same as 120Hz and 144Hz.