Resolution is how many pixels are on the screen: width x height. 1024x768 is 1024 pixels wide by 768 high. The more pixels on the screen, the more detailed the image will be, but also the more work the video card has to do in order to render the image. The usual resolutions are 640x480, 800x600, 1024x768, 1280x1024, and 1600x1200. There are a lot of others, but those are the common ones.