Wallpaper is like a sticker that covers your walls. You know how you can put stickers on your notebook to make it look pretty? Well, wallpaper is like that, but for your walls.
There are different kinds of wallpaper, just like there are different kinds of stickers. Some wallpaper has a pattern or picture on it, and some is just one color.
To put up wallpaper, you need special glue that sticks the wallpaper to the wall. Then, you use a little tool called a smoother to make sure the wallpaper is stuck down flat with no bubbles.
People use wallpaper to decorate their rooms and make them look nice. It's like putting a dress on your walls!