Next time you are by yourself with your computer, put your face right up to the monitor. If you look closely, you ll see that the image is made up of thousands of little dots. We call those dots, Pixels. Similar to your TV, these pixels, can be used to create any image or color on your monitor. Smaller pixels mean smoother, better looking images.
Larger pixels create grainy, rough images.
We measure the size of these pixels by counting how many will fit on a screen. For instance, when you buy a new computer, your screen is set to 640 pixels wide by 480 pixels tall. Your monitor screen has a fixed size. Adding more pixels to your screen will not make your physical monitor bigger. So, in order to add more pixels, they must be made smaller to fit.