A dado is very strong and functional type of joint commonly used in woodwork. The term can also be used in reference to a chair rail situated at the lower part of a wall. A dado is made by making a groove in a piece of wood after which a second piece of wood is fitted securely in the dado groove earlier made. It is commonly used in cabinet and bookshelf construction. A Dado joint is very strong and extremely reliable in cabinets and other furniture meant to hold weight.
A rail placed horizontally along the lower part of a wall may also be referred to as a Dado or a chair rail. Dado rails are used to divide or separate design elements on walls or entire rooms. A dado eases the transition between separate design materials such as a paneling and wallpaper. A dado rail can be installed to help prevent furniture from damaging the walls in a room.