What are Rails?

Definition of Rails in Construction
The horizontal piece of a sash assembly, raised panel wood, or other assembly. The vertical pieces of an assembly are called stiles as opposed to the rails which are the horizontal members. The term rail is a general construction term and can be used for almost any horizontal member that is a part of a box type visual assembly. The vertical members of this type of assembly are known as the stiles, therefore the use of both terms are constantly being used by cabinet makers, door and window suppliers, specialty door manufacturers such as garage door suppliers, etc. In some instances the exterior storefront of a building could be composed of stiles and rails with glass panels between. It all depends on the portion of the country you are building in and the descriptive terminology being used by interior decorators and architects.