Q. Describe the Vertical Frequency or cycle?
Like a Fluorescent lamp, the screen has to repeat same image many times per second to display an image to user. The frequency of this repetition is known as Vertical Frequency or Refresh Rate.
If the resolution produced by the video card and monitor resolution is properly matched you get a good quality display. Though the actual resolution attained is a physical quality of monitor. In colour systems resolution is limited by Convergence (Do the beam of the 3 colours converge exactly on same dot?) and Dot Pitch. In monochrome monitors resolution is only limited by the highest frequency signals the monitor can handle.