Wallpaper is a kind of material used to cover and decorate the interior walls of homes, offices, cafes, etc. it is one aspect of interior decoration. It is usually sold in rolls and is put onto a wall using wallpaper paste.
Wallpaper is made in long rolls, which are hung vertically on a wall. Patterned wallpapers are designed so that the pattern "repeats", and thus pieces cut from the same roll can be hung next to each other so as to continue the pattern without it being easy to see where the join between two pieces occurs.