Samsung SyncMaster VC240 User Manual page 22

Horizontal Frequency
The time taken to scan one line from the left-most position to the right-most position on the screen is called the horizontal cycle
and the reciprocal of the horizontal cycle is called the horizontal frequency. The horizontal frequency is represented in kHz.
Vertical Frequency
A panel must display the same picture on the screen tens of times every second so that humans can see the picture. This
frequency is called the vertical frequency. The vertical frequency is represented in Hz.
3-2 Using the product