What are the double buffers?
The double buffers are generally used in programs with movement. Basically while you look at the screen with an image, imagine another screen behind the first one where the next image is drawn while you look at the first one. The screens change so the first one goes to the back and you see the new screen with the new image. While you look at that, the next one is drawn behind and the screens change place and you see the new screen with the new image. This cycle continues until the program finishes. This keeps the graphics moving smoothly.
