The hinge is similar to the spine of a book and can be on the short or long side of the certificate. How your folder is designed will be determined by the orientation of your certificate. A vertical or portrait certificate (i.e. with the print reading parallel to the short dimension of the certificate) will almost always require a long side hinge with a left and right panel inside (like a book). A horizontal or landscape certificate, however, can be made with either a long top hinge (opening upwards) with a top and bottom panel inside or with a short side hinge (opening sideways) with a left and right panel inside.