$Refresh 
The process of regularly updating the images on a screen by scanning each pixel with a picture beam to make sure the image is still visible. The image on the screen is visible because tiny dots of phosphor shine. The glow from the phosphor only lasts a few tenths of a second, so the dots have to be hit by an electron picture beam to get them to glow again. This process is repeated 60 to 70 times per second.