The process of redrawing a computer display by the electron beam scanner. Since the phosphors coating the inside of the computer screen do not retain an image for more than an instant, the raster scanner needs to repeatedly "refresh" the image. The number of times per second the beam redraws the screen display is known as the refrsh rate.
The term refresh also refers to the process of reading then rewriting the data on a magnetic storage medium, which has the effect of refreshing the magnetic charge on the surface.