Alt codes are little codes you can type in to display a little image or special characters. Such as é and á. Here, we list lots of the alt codes you can use. To use an alt code, you need to hold down the ALT key on your keyboard, and then enter (while holding down alt) some numbers. These will only work if you use the numbers on the right of your keyboard, on the Num pad. So you'd hold down alt and press say 0151. You let go of 0 (still holding alt), and enter 1. And so on. Just to make that clear.